Volume 22,2024 Issue 3
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- Water circulation response and water demand situation change under “DoubleCarbon” strategy
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- Ecological regulation of algae in Middle Route of South-to-North Water Diversion Project
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- Practice and countermeasures of the great protection of the Yangtze River
- Driving effect evolution and spatial differentiation of water use change in China
- Simulation of pipeline network drainage at urban community scales based on SWMM:A case study in Fuzhou City
- Interaction mechanism between urbanization and ecological security in nine provinces of the Yellow River basin
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Abstract:
The major water transfer projects such as the East and Middle Routes of the South-to-North Water Transfer Projects are the main framework and artery of China's national water network. These long-distance water transfer projects have long routes and numerous buildings. The geographical environment and hydrological and meteorological conditions of the areas along the water transfer routes vary greatly and are complex and variable. In recent years, extreme meteorological events tend to be more frequent, more intense and more extensive. Extreme rainstorms and super standard floods occur occasionally, threatening the safe operation of these transfer projects. At the same time, with the economic and social development along the routes, some water transfer canal sections that deviated from originally urban areas have become urban canal sections. The impact of human activities and natural erosion and siltation of rivers have also led to changes in the external boundary conditions along the routes. In addition, with the increase of operating time, complex engineering geological canals and buildings are also facing their own risks of material aging and increase in hidden dangers and defects in anti-seepage and reinforcement foundations. It can be seen that long-distance water transfer projects face engineering safety risks caused by external environmental changes and internal behavior evolution during operation. To promote the high-quality development of the national water network in China, it is urgent to propose risk identification and assessment methods, and establish a full chain of risk control to ensure the safe operation of water network projects.A study was conducted based on the comprehensive risk assessment results of a major water transfer project in China. Various risk events faced by engineering safety during the operation period were analyzed, and the scheduling units between two control gates were determined as the risk assessment units. The processes of external risks transmission from left bank reservoirs, crossing rivers, etc. to water transfer projects were also analyzed. On this basis, a comprehensive risk assessment model for scheduling units based on analytic hierarchy process (AHP) was proposed. A beam type water conveyance aqueduct was selected as a case, and the identification of risk factors, risk event analysis, risk level classification standards, and risk assessment process for water conveyance buildings were explained. The scheduling unit where the aqueduct is located was taken as the assessment unit to conduct a comprehensive risk assessment using the AHP method. Finally, the risk assessment results of other scheduling units were also summarized, and the main reasons for causing high risks were discussed.The results indicate that the proposed method has good practicality. The risk value of the analyzed beam type aqueduct was 11.4, which is a relatively high risk (Level Ⅲ) due to changes in the crossing river, downward cutting of the cross-section riverbed, and insufficient burial depth of the canal piers caused by historical flood erosion. Based on the risk assessment results of the conveyance buildings, the risk value of the assessed scheduling unit was calculated. The risk of the evaluated unit project is 9.49, which also belongs to a relatively high risk (Level Ⅲ). The risk value of the water conveyance buildings is relatively high, at 10.28, with the main risk being the presence of diseases in the upstream reservoir and insufficient flood control standards, which poses a risk to the beam type aqueduct. After analyzing and calculating the risks of other scheduling units, the safety risks of the overall canal of the water transfer project mainly include the risks caused by the dam failures of the left bank reservoirs or flood discharges exceeding the flood control standards of the water transfer project, the risks of insufficient flow capacity of the crossing rivers, and the risks caused by poor discharge capacity of the left downstream buildings. Risk control measures were also proposed, mainly including the reinforcement of the left bank dangerous reservoirs and the improvement of their flood control standards.
The major water transfer projects such as the East and Middle Routes of the South-to-North Water Transfer Projects are the main framework and artery of China's national water network. These long-distance water transfer projects have long routes and numerous buildings. The geographical environment and hydrological and meteorological conditions of the areas along the water transfer routes vary greatly and are complex and variable. In recent years, extreme meteorological events tend to be more frequent, more intense and more extensive. Extreme rainstorms and super standard floods occur occasionally, threatening the safe operation of these transfer projects. At the same time, with the economic and social development along the routes, some water transfer canal sections that deviated from originally urban areas have become urban canal sections. The impact of human activities and natural erosion and siltation of rivers have also led to changes in the external boundary conditions along the routes. In addition, with the increase of operating time, complex engineering geological canals and buildings are also facing their own risks of material aging and increase in hidden dangers and defects in anti-seepage and reinforcement foundations. It can be seen that long-distance water transfer projects face engineering safety risks caused by external environmental changes and internal behavior evolution during operation. To promote the high-quality development of the national water network in China, it is urgent to propose risk identification and assessment methods, and establish a full chain of risk control to ensure the safe operation of water network projects.A study was conducted based on the comprehensive risk assessment results of a major water transfer project in China. Various risk events faced by engineering safety during the operation period were analyzed, and the scheduling units between two control gates were determined as the risk assessment units. The processes of external risks transmission from left bank reservoirs, crossing rivers, etc. to water transfer projects were also analyzed. On this basis, a comprehensive risk assessment model for scheduling units based on analytic hierarchy process (AHP) was proposed. A beam type water conveyance aqueduct was selected as a case, and the identification of risk factors, risk event analysis, risk level classification standards, and risk assessment process for water conveyance buildings were explained. The scheduling unit where the aqueduct is located was taken as the assessment unit to conduct a comprehensive risk assessment using the AHP method. Finally, the risk assessment results of other scheduling units were also summarized, and the main reasons for causing high risks were discussed.The results indicate that the proposed method has good practicality. The risk value of the analyzed beam type aqueduct was 11.4, which is a relatively high risk (Level Ⅲ) due to changes in the crossing river, downward cutting of the cross-section riverbed, and insufficient burial depth of the canal piers caused by historical flood erosion. Based on the risk assessment results of the conveyance buildings, the risk value of the assessed scheduling unit was calculated. The risk of the evaluated unit project is 9.49, which also belongs to a relatively high risk (Level Ⅲ). The risk value of the water conveyance buildings is relatively high, at 10.28, with the main risk being the presence of diseases in the upstream reservoir and insufficient flood control standards, which poses a risk to the beam type aqueduct. After analyzing and calculating the risks of other scheduling units, the safety risks of the overall canal of the water transfer project mainly include the risks caused by the dam failures of the left bank reservoirs or flood discharges exceeding the flood control standards of the water transfer project, the risks of insufficient flow capacity of the crossing rivers, and the risks caused by poor discharge capacity of the left downstream buildings. Risk control measures were also proposed, mainly including the reinforcement of the left bank dangerous reservoirs and the improvement of their flood control standards.
Abstract:
The Middle Route of the South-to-North Water Transfers Project was structured with interconnected canal pools, divided by regulating gates. During emergency situations, the synchronous operation approach was commonly adopted to shift the channel's operation from a normal water level regime to an equal-volume operation by simultaneously closing gates. This swift change in channel flow dynamics due to the abrupt hydraulic transition proved highly effective in emergency management. However, research efforts at that time focused solely on continuous gate closures, neglecting the study of hydraulic response characteristics stemming from sequential intermittent gate closures in small steps. Exploring these responses was anticipated to provide guidance for emergency gate closure strategies to effectively prevent water levels from surpassing safety thresholds.Building on the synchronization principle, the study targeted the canal pools between the Cihe gate and the Shahebei gate within the Beijing-Shijiazhuang section of the Middle Route Project. Employing the Saint-Venant equations, a one-dimensional simulation model was constructed to simulate non-uniform transient flow in open channels. This model compared the hydraulic response characteristics between sequential intermittent gate closures and continuous closures, and it simulated various hydraulic responses under different intermittent closure patterns. The analysis aimed to assess the impacts of different closure initiation times, the frequency of closures, and the duration of closures on the peak water levels upstream of the gates and the duration of hydraulic oscillations.Simulation outcomes demonstrated that, with an equal total closure time, sequential intermittent gate closures considerably reduced peak water levels and hydraulic oscillation amplitudes compared to continuous closures. These closures substantially shortened the time required for stability, allowing the canal pools to rapidly regain stability. Peak water levels upstream of the gates initially declined and then increased as the closure initiation time was adjusted. Conversely, the stability duration of hydraulic oscillations decreased as the closure initiation time was altered. Initiating intermittent closures as precipitation waves approached downstream gates facilitated a reduction in water levels during the closure period, slowing the buildup of water resulting from gate closure. This action effectively minimized peak water levels upstream while significantly reducing the required duration for stability. The increased frequency of intermittent closures led to higher peak water levels upstream and reduced the rate of water level reduction. Yet, it notably reduced the duration of hydraulic oscillations. Despite slightly prolonging the stability time needed for upstream water levels, concentrating closures maximized the utilization of precipitation waves, achieving the most substantial reduction in upstream water levels. Both peak water levels and the duration of hydraulic oscillations initially decreased and then increased with longer closure durations. Closure duration directly influenced the duration of action for precipitation waves and gate closure speed. Optimal closure duration, slightly less than half of the total closure time, resulted in the highest reduction rates of peak water levels and shorter stability times.The hydraulic response characteristics of sequential intermittent gate closures were closely associated with water wave dynamics, primarily influenced by canal pool dimensions, depth, and flow velocity. Setting a single intermittent closure as precipitation waves approached downstream gates, with a duration slightly less than half of the total closure time, maximized water reduction and shortened stability time. These findings, derived from the Cihe gate to Shahebei gate canal segment, were deemed broadly applicable to other segments within the Middle Route Project.
The Middle Route of the South-to-North Water Transfers Project was structured with interconnected canal pools, divided by regulating gates. During emergency situations, the synchronous operation approach was commonly adopted to shift the channel's operation from a normal water level regime to an equal-volume operation by simultaneously closing gates. This swift change in channel flow dynamics due to the abrupt hydraulic transition proved highly effective in emergency management. However, research efforts at that time focused solely on continuous gate closures, neglecting the study of hydraulic response characteristics stemming from sequential intermittent gate closures in small steps. Exploring these responses was anticipated to provide guidance for emergency gate closure strategies to effectively prevent water levels from surpassing safety thresholds.Building on the synchronization principle, the study targeted the canal pools between the Cihe gate and the Shahebei gate within the Beijing-Shijiazhuang section of the Middle Route Project. Employing the Saint-Venant equations, a one-dimensional simulation model was constructed to simulate non-uniform transient flow in open channels. This model compared the hydraulic response characteristics between sequential intermittent gate closures and continuous closures, and it simulated various hydraulic responses under different intermittent closure patterns. The analysis aimed to assess the impacts of different closure initiation times, the frequency of closures, and the duration of closures on the peak water levels upstream of the gates and the duration of hydraulic oscillations.Simulation outcomes demonstrated that, with an equal total closure time, sequential intermittent gate closures considerably reduced peak water levels and hydraulic oscillation amplitudes compared to continuous closures. These closures substantially shortened the time required for stability, allowing the canal pools to rapidly regain stability. Peak water levels upstream of the gates initially declined and then increased as the closure initiation time was adjusted. Conversely, the stability duration of hydraulic oscillations decreased as the closure initiation time was altered. Initiating intermittent closures as precipitation waves approached downstream gates facilitated a reduction in water levels during the closure period, slowing the buildup of water resulting from gate closure. This action effectively minimized peak water levels upstream while significantly reducing the required duration for stability. The increased frequency of intermittent closures led to higher peak water levels upstream and reduced the rate of water level reduction. Yet, it notably reduced the duration of hydraulic oscillations. Despite slightly prolonging the stability time needed for upstream water levels, concentrating closures maximized the utilization of precipitation waves, achieving the most substantial reduction in upstream water levels. Both peak water levels and the duration of hydraulic oscillations initially decreased and then increased with longer closure durations. Closure duration directly influenced the duration of action for precipitation waves and gate closure speed. Optimal closure duration, slightly less than half of the total closure time, resulted in the highest reduction rates of peak water levels and shorter stability times.The hydraulic response characteristics of sequential intermittent gate closures were closely associated with water wave dynamics, primarily influenced by canal pool dimensions, depth, and flow velocity. Setting a single intermittent closure as precipitation waves approached downstream gates, with a duration slightly less than half of the total closure time, maximized water reduction and shortened stability time. These findings, derived from the Cihe gate to Shahebei gate canal segment, were deemed broadly applicable to other segments within the Middle Route Project.
Abstract:
The real-time hydrological data such as water level and discharge of the main canal of the Middle Route of the South-to-North Water Transfers Project are affected by external disturbances, measurement system errors and other factors. The ill-conditioned hydrological data will cause the calculation distortion of the scheduling model, and even lead to the failure of the calculation.Aimed at the logical errors in the upstream and downstream flow data space and the jump of the time series of water level data, the water balance model based on particle swarm optimization and the exponential weighted moving average model were established respectively, and the pathological water regime data was cleaned horizontally and vertically in space and time. Taken the channel section between the Yellow River controlling gate and the Zhanghe River controlling gate as a typical research interval, the flow inversion point was automatically identified by the model. The flow data of 12 controlling gates and 26 water diversion points involved in the channel section were uniformly corrected to realize the rationality of upstream and downstream logic. At the same time, the Yanhe controlling gate in the research section was selected as the representative. Under the basic stable state of operation within 48 hours, the water level data sequence in front of the gate every 2 hours was analyzed, and the jump data was automatically identified and reasonably corrected.The results showed that the model established could automatically identify the pathological water regime data and carried out intelligent cleaning. The processed data was able to better meet the needs of water transfer scheduling analysis and decision-making. So the model has the value of popularization and application.
The real-time hydrological data such as water level and discharge of the main canal of the Middle Route of the South-to-North Water Transfers Project are affected by external disturbances, measurement system errors and other factors. The ill-conditioned hydrological data will cause the calculation distortion of the scheduling model, and even lead to the failure of the calculation.Aimed at the logical errors in the upstream and downstream flow data space and the jump of the time series of water level data, the water balance model based on particle swarm optimization and the exponential weighted moving average model were established respectively, and the pathological water regime data was cleaned horizontally and vertically in space and time. Taken the channel section between the Yellow River controlling gate and the Zhanghe River controlling gate as a typical research interval, the flow inversion point was automatically identified by the model. The flow data of 12 controlling gates and 26 water diversion points involved in the channel section were uniformly corrected to realize the rationality of upstream and downstream logic. At the same time, the Yanhe controlling gate in the research section was selected as the representative. Under the basic stable state of operation within 48 hours, the water level data sequence in front of the gate every 2 hours was analyzed, and the jump data was automatically identified and reasonably corrected.The results showed that the model established could automatically identify the pathological water regime data and carried out intelligent cleaning. The processed data was able to better meet the needs of water transfer scheduling analysis and decision-making. So the model has the value of popularization and application.
Abstract:
Global climate change and human activities, have led to a significant rise in the occurrence and intensity of extreme hydrological events in the basin. To deal with this situation and ensure the security of the country’s water supply, the national water network project was proposed. The South-to-North Water Transfers Project served as the primary framework to achieve this objective. Since the implementation of the Eastern Route of the South-to-North Water Transfers Project, water security has been significantly improved. However, Dongping Lake, as an important node reservoir and the last stage of regulation reservoir of the Eastern Route of the South-to-North Water Transfers Project, was underutilized for a comprehensive reservoir.To enhance the water supply benefit of the second phase of the Eastern Route and the resilience of the water resources system to extreme events, a new scheme was proposed by the surplus storage capacity of Dongping Lake to regulate water inflow into the lake. First, the concept of surplus storage capacity was defined, and the value of surplus storage capacity and variation were analysed according to the parameters of discharge into the lake, water consumption around the lake and the evapotranspiration loss of Dongping Lake Reservoir. Second, based on the principle of reservoir water balance, sequential logic of multi-source joint dispatching decision and multi-objective optimisation, different regulation schemes of Dongping Lake were proposed for the second phase of the South-to-North Water Transfers Project. The optimal storage scheme of Dongping Lake was recommended by comparing the application effects of different implementation schemes according to the influence of the guarantee rate of water consumption around the lake, the water demand of Dongping Lake, the water inflow into Yellow Lake and the safety of engineering. The optimal storage scheme could provide a concrete reference for the actual operation and management of the Dongping Lake Reservoir. The results show that: the average monthly surplus storage capacity of Dongping Lake from 1956 to 2016 was 117 million m3. It is feasible to use the surplus storage capacity of Dongping Lake to transfer and store the incoming water from the Eastern Route when the incoming water from Dawen River is dry and the water level of Dongping Lake is low. The scheme to regulate the storage capacity of Dongping Lake was recommended by analysing the effects of different schemes on the guarantee rate of water consumption around the lake, the water demand of Dongping Lake, the water inflow into Yellow River and the safety of engineering. Although the scheme has little effect on reducing the amount of water transferred from the Eastern Route, it increased the storage capacity of the Eastern Route by 362 million m3.The scheme of Dongping Lake needs to be adjusted in order to adapt to the changes in the external environment and to realise the comprehensive functions in the new time period.The scheme of Dongping Lake storage capacity regulation could make full use of the storage capacity of Dongping Lake and increase the flexibility of Dongping Lake reservoir dispatch. At the same time, this regulation scheme improves the resilience of the reservoir to extreme hydrological events. This is of great significance in enhancing the benefits of comprehensive reservoir utilisation and ensuring the water security in the basin.
Global climate change and human activities, have led to a significant rise in the occurrence and intensity of extreme hydrological events in the basin. To deal with this situation and ensure the security of the country’s water supply, the national water network project was proposed. The South-to-North Water Transfers Project served as the primary framework to achieve this objective. Since the implementation of the Eastern Route of the South-to-North Water Transfers Project, water security has been significantly improved. However, Dongping Lake, as an important node reservoir and the last stage of regulation reservoir of the Eastern Route of the South-to-North Water Transfers Project, was underutilized for a comprehensive reservoir.To enhance the water supply benefit of the second phase of the Eastern Route and the resilience of the water resources system to extreme events, a new scheme was proposed by the surplus storage capacity of Dongping Lake to regulate water inflow into the lake. First, the concept of surplus storage capacity was defined, and the value of surplus storage capacity and variation were analysed according to the parameters of discharge into the lake, water consumption around the lake and the evapotranspiration loss of Dongping Lake Reservoir. Second, based on the principle of reservoir water balance, sequential logic of multi-source joint dispatching decision and multi-objective optimisation, different regulation schemes of Dongping Lake were proposed for the second phase of the South-to-North Water Transfers Project. The optimal storage scheme of Dongping Lake was recommended by comparing the application effects of different implementation schemes according to the influence of the guarantee rate of water consumption around the lake, the water demand of Dongping Lake, the water inflow into Yellow Lake and the safety of engineering. The optimal storage scheme could provide a concrete reference for the actual operation and management of the Dongping Lake Reservoir. The results show that: the average monthly surplus storage capacity of Dongping Lake from 1956 to 2016 was 117 million m3. It is feasible to use the surplus storage capacity of Dongping Lake to transfer and store the incoming water from the Eastern Route when the incoming water from Dawen River is dry and the water level of Dongping Lake is low. The scheme to regulate the storage capacity of Dongping Lake was recommended by analysing the effects of different schemes on the guarantee rate of water consumption around the lake, the water demand of Dongping Lake, the water inflow into Yellow River and the safety of engineering. Although the scheme has little effect on reducing the amount of water transferred from the Eastern Route, it increased the storage capacity of the Eastern Route by 362 million m3.The scheme of Dongping Lake needs to be adjusted in order to adapt to the changes in the external environment and to realise the comprehensive functions in the new time period.The scheme of Dongping Lake storage capacity regulation could make full use of the storage capacity of Dongping Lake and increase the flexibility of Dongping Lake reservoir dispatch. At the same time, this regulation scheme improves the resilience of the reservoir to extreme hydrological events. This is of great significance in enhancing the benefits of comprehensive reservoir utilisation and ensuring the water security in the basin.
Abstract:
Existing data has indicated that the seepage amount in the dam is inversely proportional to the temperature. Higher temperatures result in less seepage, while lower temperatures lead to more seepage. Seepage mainly occurs in the U3 section of the Wanyao Reservoir, and the effects of several anti-seepage measures have not been very significant. Since the seepage channel in the U3 section directly leads to the gallery in the front of the dam and is closely related to the reservoir water level, the impact of the current water level on seepage can be considered significant, and the lag effect of the water level on seepage can be ignored. Therefore, considering the frequent occurrence of extreme weather in recent years, such as high temperatures in summer and freezing conditions in winter, which can have a significant impact on existing seepage channels in the dam and even pose safety hazards, it is necessary to study the seepage amount of the Wanyao Reservoir under conditions of high water level and low temperature.Temperature was calculated using the Cubic Law, an analytical expression for the size of the seepage channel in the U3 section, and the relationship between temperature and measured seepage amount. A three-dimensional groundwater flow numerical model was established using COMSOL software. The model parameters were identified and validated using the measured water level data, and the seepage amount of the dam under different operating conditions was predicted. The model parameter inversion results show that, with the exception of a relative error of 1.53% in the U504 hole, the relative errors in the other observation holes are all less than 1%, indicating that the model has a good overall fit to the observation data. The model's predictions show that: (1) At a low temperature of 0 ℃, the seepage amount reaches its maximum at 0.68 L/s, which decreases to 0.38 L/s at a high temperature of 20 ℃, and further reduces to 8.71×10?5L/s after repairing the seepage channel at 0 ℃. (2) The analytical and numerical simulation calculations of the U3 seepage amount are in good agreement, demonstrating the reliability of the seepage amount calculation. (3) After anti-seepage repairs, a simulated flood with a return period of one hundred years, i.e., a design flood level of 195.29 m and a check flood level of 195.5 m, results in a dam seepage amount of 0.67 L/s, with a slightly reduced dam foundation seepage amount of 2.16 L/s and 2.14 L/s, respectively.In conclusion: (1) Temperature and seepage have a clear negative correlation, with rising temperatures significantly decreasing dam seepage. The equivalent width of the dam seepage channel was calculated using the Cubic Law and the dam as a fracture, providing parameters for numerical simulations. (2) COMSOL software was used to calculate dam foundation seepage under different temperatures and water levels based on the geological conditions and dam structure at the dam site. The results show that seepage in the U3 section decreases with increasing temperature, with 0.68 L/s at 0 ℃ and 0.05 L/s at 40 °C, a difference of 12.6 times, indicating that low-temperature and high-water-level environments have a significant influence on seepage. (3) Seepage significantly decreases after anti-seepage reinforcement, therefore, it is necessary to promptly grout and seal the seepage channels to reduce the reservoir's seepage and ensure its normal and safe operation.
Existing data has indicated that the seepage amount in the dam is inversely proportional to the temperature. Higher temperatures result in less seepage, while lower temperatures lead to more seepage. Seepage mainly occurs in the U3 section of the Wanyao Reservoir, and the effects of several anti-seepage measures have not been very significant. Since the seepage channel in the U3 section directly leads to the gallery in the front of the dam and is closely related to the reservoir water level, the impact of the current water level on seepage can be considered significant, and the lag effect of the water level on seepage can be ignored. Therefore, considering the frequent occurrence of extreme weather in recent years, such as high temperatures in summer and freezing conditions in winter, which can have a significant impact on existing seepage channels in the dam and even pose safety hazards, it is necessary to study the seepage amount of the Wanyao Reservoir under conditions of high water level and low temperature.Temperature was calculated using the Cubic Law, an analytical expression for the size of the seepage channel in the U3 section, and the relationship between temperature and measured seepage amount. A three-dimensional groundwater flow numerical model was established using COMSOL software. The model parameters were identified and validated using the measured water level data, and the seepage amount of the dam under different operating conditions was predicted. The model parameter inversion results show that, with the exception of a relative error of 1.53% in the U504 hole, the relative errors in the other observation holes are all less than 1%, indicating that the model has a good overall fit to the observation data. The model's predictions show that: (1) At a low temperature of 0 ℃, the seepage amount reaches its maximum at 0.68 L/s, which decreases to 0.38 L/s at a high temperature of 20 ℃, and further reduces to 8.71×10?5L/s after repairing the seepage channel at 0 ℃. (2) The analytical and numerical simulation calculations of the U3 seepage amount are in good agreement, demonstrating the reliability of the seepage amount calculation. (3) After anti-seepage repairs, a simulated flood with a return period of one hundred years, i.e., a design flood level of 195.29 m and a check flood level of 195.5 m, results in a dam seepage amount of 0.67 L/s, with a slightly reduced dam foundation seepage amount of 2.16 L/s and 2.14 L/s, respectively.In conclusion: (1) Temperature and seepage have a clear negative correlation, with rising temperatures significantly decreasing dam seepage. The equivalent width of the dam seepage channel was calculated using the Cubic Law and the dam as a fracture, providing parameters for numerical simulations. (2) COMSOL software was used to calculate dam foundation seepage under different temperatures and water levels based on the geological conditions and dam structure at the dam site. The results show that seepage in the U3 section decreases with increasing temperature, with 0.68 L/s at 0 ℃ and 0.05 L/s at 40 °C, a difference of 12.6 times, indicating that low-temperature and high-water-level environments have a significant influence on seepage. (3) Seepage significantly decreases after anti-seepage reinforcement, therefore, it is necessary to promptly grout and seal the seepage channels to reduce the reservoir's seepage and ensure its normal and safe operation.
Effect of ecological water replenishment on groundwater recharge in the Beijing-Hangzhou Grand Canal
Abstract:
Ecological water replenishment is an important measure to improve the ecological environment of rivers and lakes and reduce the groundwater deficit. The dynamic change of groundwater level is the most intuitive index to evaluate the effect of the short-time ecological water replenishment. In order to scientifically evaluate the effect of the ecological water replenishment on the Beijing-Hangzhou Grand Canal since 2022, it is necessary to explore the dynamic changes of the groundwater levels in different reaches of the Grand Canal.Based on the groundwater level data from 419 phreatic water and 173 confined water monitoring wells along the Beijing-Hangzhou Grand Canal (the north section of the Yellow River, including Xiao Canal, Wei Canal, South Canal, North Canal, and Tonghui River) during the replenishment period in 2022-2023, the river channel infiltration was calculated by the water balance method, and the variations of the groundwater level was analyzed along the river channel and in the agricultural irrigation water source replacement regions.Results showed that: (1) The volume of ecological water replenishment for the Beijing-Hangzhou Grand Canal in 2023 was 926 million cubic meters, and the infiltration volume was 149 million cubic meters. Compared to the lining channels such as Xiao Canal, North Canal, and Tonghui River, Wei Canal and South Canal had a high permeability, which can recharge groundwater around the river channel more efficiency. (2) During the replenishment period, the phreatic water level in the range of 0~10 km around the river decreased 0.80 m, which confirmed that the current water replenishment amount is not enough to fully eliminate the impact of spring irrigation water withdrawals in March to May on the groundwater level. (3) The average decrease of groundwater level in regions beyond 10 km from the center line of the river channel (unaffected area) was 1.01 m. And the average decrease of groundwater level in regions within 10 km from the center line of the river channel was 0.80 m, which was significantly lower than that in the unaffected area, indicating that ecological water replenishment effectively mitigated the downward trend of groundwater level. (4) Groundwater level has risen by 0.48 m compared to the same period of last year and the decrease of groundwater level has reduced by 0.19 m during the spring irrigation period, indicating the positive impact of replenishment on the groundwater level recovery. (5) There had a delayed effect on the response of the groundwater level to the water replenishment, which was shown as the closer distance to the river, the smaller decrease of the groundwater level. (6) In the agricultural irrigation water source replacement regions, compared with the same period of last year, the confined water and phreatic water levels have risen by 3.17 m and 0.27 m respectively, which showed the water source replacement can effectively alleviate the decline in groundwater levels caused by irrigation water withdrawals.This study is of great significance to grasp the changing law of groundwater level by ecological water replenishment, which can provide the basis for further optimization of ecological water replenishment plan. Changes in groundwater levels in the Beijing-Hangzhou Grand Canal after the two consecutive years of ecological water replenishment indicated that the downward trend in groundwater levels due to irrigation withdrawals was difficult to reverse through the ecological recharge. While continuous implementation of ecological replenishment on rivers with strong infiltration and high irrigation water demand can promote the recovery of groundwater levels effectively.
Ecological water replenishment is an important measure to improve the ecological environment of rivers and lakes and reduce the groundwater deficit. The dynamic change of groundwater level is the most intuitive index to evaluate the effect of the short-time ecological water replenishment. In order to scientifically evaluate the effect of the ecological water replenishment on the Beijing-Hangzhou Grand Canal since 2022, it is necessary to explore the dynamic changes of the groundwater levels in different reaches of the Grand Canal.Based on the groundwater level data from 419 phreatic water and 173 confined water monitoring wells along the Beijing-Hangzhou Grand Canal (the north section of the Yellow River, including Xiao Canal, Wei Canal, South Canal, North Canal, and Tonghui River) during the replenishment period in 2022-2023, the river channel infiltration was calculated by the water balance method, and the variations of the groundwater level was analyzed along the river channel and in the agricultural irrigation water source replacement regions.Results showed that: (1) The volume of ecological water replenishment for the Beijing-Hangzhou Grand Canal in 2023 was 926 million cubic meters, and the infiltration volume was 149 million cubic meters. Compared to the lining channels such as Xiao Canal, North Canal, and Tonghui River, Wei Canal and South Canal had a high permeability, which can recharge groundwater around the river channel more efficiency. (2) During the replenishment period, the phreatic water level in the range of 0~10 km around the river decreased 0.80 m, which confirmed that the current water replenishment amount is not enough to fully eliminate the impact of spring irrigation water withdrawals in March to May on the groundwater level. (3) The average decrease of groundwater level in regions beyond 10 km from the center line of the river channel (unaffected area) was 1.01 m. And the average decrease of groundwater level in regions within 10 km from the center line of the river channel was 0.80 m, which was significantly lower than that in the unaffected area, indicating that ecological water replenishment effectively mitigated the downward trend of groundwater level. (4) Groundwater level has risen by 0.48 m compared to the same period of last year and the decrease of groundwater level has reduced by 0.19 m during the spring irrigation period, indicating the positive impact of replenishment on the groundwater level recovery. (5) There had a delayed effect on the response of the groundwater level to the water replenishment, which was shown as the closer distance to the river, the smaller decrease of the groundwater level. (6) In the agricultural irrigation water source replacement regions, compared with the same period of last year, the confined water and phreatic water levels have risen by 3.17 m and 0.27 m respectively, which showed the water source replacement can effectively alleviate the decline in groundwater levels caused by irrigation water withdrawals.This study is of great significance to grasp the changing law of groundwater level by ecological water replenishment, which can provide the basis for further optimization of ecological water replenishment plan. Changes in groundwater levels in the Beijing-Hangzhou Grand Canal after the two consecutive years of ecological water replenishment indicated that the downward trend in groundwater levels due to irrigation withdrawals was difficult to reverse through the ecological recharge. While continuous implementation of ecological replenishment on rivers with strong infiltration and high irrigation water demand can promote the recovery of groundwater levels effectively.
Abstract:
Assessing ecological flow is an important measure to enhance the ecological function of reservoirs and maintain the healthy life of rivers. The ecological flow process proposed using cutting-edge methods generally includes components such as base flow, high flow pulses, and floods. The various flow regime is crucial for the ecological health of rivers, but the complex ecological flow process makes it difficult to put it into practical application. How to face practical needs and coordinate the scientificity and practicality of the ecological flow process is a difficult problem that urgently needs to be solved in this field. In 2022, the Ministry of Water Resources of the People's Republic of China launched the pilot work of ecological flow assessment and guarantee for constructed water conservancy and hydropower projects, aiming to strengthen the management and supervision of ecological flow. The Longyangxia Reservoir and Liujiaxia Reservoir in the main stream of the Yellow River have been included in the list of pilot projects. Longyangxia Reservoir and Liujiaxia Reservoir were constructed long ago and there is no ecological flow release task in these two reservoirs scheduling currently. Taking Longyangxia Reservoir and Liujiaxia Reservoir as examples, a method for ecological flow assessment based on practical needs for cascade reservoirs is proposed. Firstly, the Tennant method and QP method are used to calculate the reasonable range of ecological flow. When using the Tennant method, the range of ecological flow during periods of low water is chosen as 10% to 40% of the annual average natural flow, while during periods of high water, the range of ecological flow is chosen as 30% to 60% of the annual average natural flow. When using the QP method, the frequency is selected as 90%. Then, the flow control indicators in the main affected river sections of cascade reservoirs approved by the government and the demand range for outflow from the existing scheduling tasks of cascade reservoirs are sorted out. After coordinating the needs of all parties, the initial value of ecological flow is proposed. Next, the guarantee capacity of ecological flow is analyzed. By establishing a simulation model for cascade reservoirs operation, the reservoirs' ability to guarantee the ecological flow is simulated. Meanwhile, a long series of measured reservoir outflow data is used to calculate the historical guarantee rate of ecological flow. If the guarantee capacity is insufficient, it is necessary to adjust the ecological flow. For cascade reservoirs, it is also necessary to analyze whether the ecological flow discharged from upstream reservoirs can meet the ecological flow requirements of downstream reservoirs. After coordination analysis, the recommended ecological flow value is finally obtained. Results show that the ecological flow of Longyangxia Reservoir is 400 m3/s from May to June, 200m3/s in other time periods. The ecological flow of Liujiaxia Reservoir is 285 m3/s. The long-term guarantee rates of two reservoirs are not less than 90%. The Longyangxia Reservoir and Liujiaxia Reservoir both have good ecological flow guarantee capabilities. The simulated guarantee rates are both 100%. The historical guarantee rates during the 1990-2019 hydrological year were 95% and 97%, respectively. However, ecological flow guarantee still faces risks under extreme low water conditions, such as the historical guarantee rates were 81% and 82% in the 2002 hydrological year, respectively. Implementing ecological flow in Longyangxia Reservoir and Liujiaxia Reservoir will face two prominent issues: ecological flow guarantee during sensitive periods under extreme low water conditions and the impact of interval cascade power stations. May to June (sensitive periods) is the concentrated spawning period for fish in the section from Longyangxia Reservoir to Liujiaxia Reservoir, which requires a large flow to stimulate spawning and form suitable spawning grounds. However, historical guarantee rate in May to June was much lower than other periods, indicating the need to increase the priority of ecological flow release during sensitive periods in the future. There are 11 hydropower stations built between Longyangxia Reservoir and Liujiaxia Reservoir. Although the storage capacity of these hydropower stations are relatively small, it may still affect the daily flow process. It is suggested to promote the ecological flow assessment work of the cascade power stations in this section in the future.
Assessing ecological flow is an important measure to enhance the ecological function of reservoirs and maintain the healthy life of rivers. The ecological flow process proposed using cutting-edge methods generally includes components such as base flow, high flow pulses, and floods. The various flow regime is crucial for the ecological health of rivers, but the complex ecological flow process makes it difficult to put it into practical application. How to face practical needs and coordinate the scientificity and practicality of the ecological flow process is a difficult problem that urgently needs to be solved in this field. In 2022, the Ministry of Water Resources of the People's Republic of China launched the pilot work of ecological flow assessment and guarantee for constructed water conservancy and hydropower projects, aiming to strengthen the management and supervision of ecological flow. The Longyangxia Reservoir and Liujiaxia Reservoir in the main stream of the Yellow River have been included in the list of pilot projects. Longyangxia Reservoir and Liujiaxia Reservoir were constructed long ago and there is no ecological flow release task in these two reservoirs scheduling currently. Taking Longyangxia Reservoir and Liujiaxia Reservoir as examples, a method for ecological flow assessment based on practical needs for cascade reservoirs is proposed. Firstly, the Tennant method and QP method are used to calculate the reasonable range of ecological flow. When using the Tennant method, the range of ecological flow during periods of low water is chosen as 10% to 40% of the annual average natural flow, while during periods of high water, the range of ecological flow is chosen as 30% to 60% of the annual average natural flow. When using the QP method, the frequency is selected as 90%. Then, the flow control indicators in the main affected river sections of cascade reservoirs approved by the government and the demand range for outflow from the existing scheduling tasks of cascade reservoirs are sorted out. After coordinating the needs of all parties, the initial value of ecological flow is proposed. Next, the guarantee capacity of ecological flow is analyzed. By establishing a simulation model for cascade reservoirs operation, the reservoirs' ability to guarantee the ecological flow is simulated. Meanwhile, a long series of measured reservoir outflow data is used to calculate the historical guarantee rate of ecological flow. If the guarantee capacity is insufficient, it is necessary to adjust the ecological flow. For cascade reservoirs, it is also necessary to analyze whether the ecological flow discharged from upstream reservoirs can meet the ecological flow requirements of downstream reservoirs. After coordination analysis, the recommended ecological flow value is finally obtained. Results show that the ecological flow of Longyangxia Reservoir is 400 m3/s from May to June, 200m3/s in other time periods. The ecological flow of Liujiaxia Reservoir is 285 m3/s. The long-term guarantee rates of two reservoirs are not less than 90%. The Longyangxia Reservoir and Liujiaxia Reservoir both have good ecological flow guarantee capabilities. The simulated guarantee rates are both 100%. The historical guarantee rates during the 1990-2019 hydrological year were 95% and 97%, respectively. However, ecological flow guarantee still faces risks under extreme low water conditions, such as the historical guarantee rates were 81% and 82% in the 2002 hydrological year, respectively. Implementing ecological flow in Longyangxia Reservoir and Liujiaxia Reservoir will face two prominent issues: ecological flow guarantee during sensitive periods under extreme low water conditions and the impact of interval cascade power stations. May to June (sensitive periods) is the concentrated spawning period for fish in the section from Longyangxia Reservoir to Liujiaxia Reservoir, which requires a large flow to stimulate spawning and form suitable spawning grounds. However, historical guarantee rate in May to June was much lower than other periods, indicating the need to increase the priority of ecological flow release during sensitive periods in the future. There are 11 hydropower stations built between Longyangxia Reservoir and Liujiaxia Reservoir. Although the storage capacity of these hydropower stations are relatively small, it may still affect the daily flow process. It is suggested to promote the ecological flow assessment work of the cascade power stations in this section in the future.
Abstract:
For the non-stationary hydrological time series, it is of great importance to explore its formation with attribution analysis to understand the hydrological process and solve the problem of water resources. Under the influence of both climate change and human activity, hydrological process in the Miyun Reservoir basin shows significantly non-stationary characteristics, while there are great differences in the results of attribution in this basin. In order to accurately reveal the causes of runoff changes in the Miyun Reservoir basin, the whole period (1960-2019) was divided into three parts: 1960-1979 for the baseline period, 1980-1998 for the change period Ⅰ, and 1999-2019 for the change period Ⅱ based on the detection result of the non-stationary characteristics of precipitation-runoff. The SWAT method, the elastic coefficient method, and the water balance method based on Budyko theory were used for attribution, and then model suitable for attribution in the Miyun Reservoir basin was selected according to the attribution results and basin characteristics. Based on the selected model, length and position of baseline period were changed to further explore the influence of baseline period on the attribution result.It was shown that attributions of elastic coefficient method and water balance method based on Budyko were similar, while the attribution of SWAT method was quite different. In the change period Ⅰ, contribution of human activities to runoff changes show as SWAT method < elastic coefficient method < water balance method. And in change period Ⅱ, results of the two methods on Budyko both showed that human activity was the main reason for the decrease of runoff, while result of SWAT showed that the impact of climate change on runoff far exceeded the impact of human activities, and became the dominant factor affecting the runoff. Cross-validation of multi-method attributions showed that the water balance method based on Budyko theory was more suitable for the attribution of runoff changes due to the construction of hydraulic projects and frequent inter-basin water transfer in the Miyun Reservoir basin. Based on the selected model, it was found that the results of attribution tended to be stable as the length of the baseline period reached 16 years. Reduction effect of human activities on runoff would be overestimated while the baseline period was shorter than 16 years. And the calculated water reduction effect of human activities was larger when the baseline period was closer to the initial position of the whole period. Considering both the effects of model and baseline period, it was concluded that human activities were the dominant factor in the runoff changes in Miyun Reservoir basin; its reduction effect on runoff fluctuated from ?128.32% to ?119.56% during the change period Ⅰ, and was about ?75.58% to ?70.70% during the change period Ⅱ. These results are helpful to improve the scientific understanding of the complex changes of the runoff and its attribution in Miyun Reservoir basin.
For the non-stationary hydrological time series, it is of great importance to explore its formation with attribution analysis to understand the hydrological process and solve the problem of water resources. Under the influence of both climate change and human activity, hydrological process in the Miyun Reservoir basin shows significantly non-stationary characteristics, while there are great differences in the results of attribution in this basin. In order to accurately reveal the causes of runoff changes in the Miyun Reservoir basin, the whole period (1960-2019) was divided into three parts: 1960-1979 for the baseline period, 1980-1998 for the change period Ⅰ, and 1999-2019 for the change period Ⅱ based on the detection result of the non-stationary characteristics of precipitation-runoff. The SWAT method, the elastic coefficient method, and the water balance method based on Budyko theory were used for attribution, and then model suitable for attribution in the Miyun Reservoir basin was selected according to the attribution results and basin characteristics. Based on the selected model, length and position of baseline period were changed to further explore the influence of baseline period on the attribution result.It was shown that attributions of elastic coefficient method and water balance method based on Budyko were similar, while the attribution of SWAT method was quite different. In the change period Ⅰ, contribution of human activities to runoff changes show as SWAT method < elastic coefficient method < water balance method. And in change period Ⅱ, results of the two methods on Budyko both showed that human activity was the main reason for the decrease of runoff, while result of SWAT showed that the impact of climate change on runoff far exceeded the impact of human activities, and became the dominant factor affecting the runoff. Cross-validation of multi-method attributions showed that the water balance method based on Budyko theory was more suitable for the attribution of runoff changes due to the construction of hydraulic projects and frequent inter-basin water transfer in the Miyun Reservoir basin. Based on the selected model, it was found that the results of attribution tended to be stable as the length of the baseline period reached 16 years. Reduction effect of human activities on runoff would be overestimated while the baseline period was shorter than 16 years. And the calculated water reduction effect of human activities was larger when the baseline period was closer to the initial position of the whole period. Considering both the effects of model and baseline period, it was concluded that human activities were the dominant factor in the runoff changes in Miyun Reservoir basin; its reduction effect on runoff fluctuated from ?128.32% to ?119.56% during the change period Ⅰ, and was about ?75.58% to ?70.70% during the change period Ⅱ. These results are helpful to improve the scientific understanding of the complex changes of the runoff and its attribution in Miyun Reservoir basin.
GE?Shiyang
1, 2，GUAN?Tiesheng
2, 3, 4，LIU?Yanli
2, 3, 4, 5，JIN?Junliang
2, 3, 4，
WANG?Guoqing
2, 3, 4，LIU?Cuishan
2, 3, 4，JU?Qin
1, 5
Abstract:
Potential evapotranspiration is an effective tool for monitoring energy balance and humidity transfer, and can serve as an important indicator of whether extreme meteorological events occur. The Yarlung Zangbo River basin is extremely sensitive and vulnerable to climate change, with complex terrain conditions, large geographical span, sparse observation stations in the basin, great difficulty in ground observation, and shortage of data, making it difficult to obtain high-precision and large-scale potential evapotranspiration data. At present, Penman Monteith formula is mainly used to estimate the potential evapotranspiration in the the Yarlung Zangbo River basin, and there are relatively few studies on the evaluation and fusion of potential evapotranspiration remote sensing products. Therefore, with the Yarlung Zangbo River basin as the research area, the multi-source remote sensing datas are used to fuse a set of potential evapotranspiration fusion data with better adaptability, in order to reveal the potential evapotranspiration changes in the Yarlung Zangbo River basin, and provide a scientific basis for the study of water and heat cycle and ecological hydrological processes of the basin under global climate change.Based on the evaporation pan datas observed by the the Yarlung Zangbo River basin meteorological station from 2001 to 2018, Pearson correlation coefficient, bias and root mean square error were selected to analyze and evaluate four commonly used remote sensing potential evapotranspiration products GLEAM, MOD16A2, GLDAS_Noah and ERA5. Then, a better adaptive potential evapotranspiration fusion data was generated by Triple Collocation (TC) method and least square method, and the spatiotemporal distribution of potential evapotranspiration in the study area was discussed. At site scale and basin scale, ERA5 potential evapotranspiration products had good adaptability in the Yarlung Zangbo River, and its assessment accuracy was significantly better than GLEAM, MOD16A2 and GLDAS_Noah potential evapotranspiration products. In terms of spatial distribution of station accuracy, except GLEAM, the correlation of the other three remote sensing data was most significant in the middle reaches of the basin. The relative deviation of MOD16A2 and ERA5 was small, and the spatial distribution of their root mean square error of the two was opposite to the relative deviation. The weights of MOD16A2, GLDAS_Noah and ERA5 remote sensing datas in the fused data were 31.12%, 30.64% and 38.24%, respectively. The uncertainty analysis of the three remote sensing products showed that the spatial distribution of errors in the upper reaches of the Yarlung Zangbo River basin was gradually decreasing from north to south, but the spatial distribution of errors in other parts was different. The spatial distribution of weights was basically opposite to the spatial distribution of errors. The four types of data had large multi-year mean potential evapotranspiration in the middle of the Yarlung Zangbo River basin, and the difference was whether there was a greater potential evapotranspiration in the southeast corner of the basin. The multi-year average potential evapotranspiration was in the order: ERA5
Potential evapotranspiration is an effective tool for monitoring energy balance and humidity transfer, and can serve as an important indicator of whether extreme meteorological events occur. The Yarlung Zangbo River basin is extremely sensitive and vulnerable to climate change, with complex terrain conditions, large geographical span, sparse observation stations in the basin, great difficulty in ground observation, and shortage of data, making it difficult to obtain high-precision and large-scale potential evapotranspiration data. At present, Penman Monteith formula is mainly used to estimate the potential evapotranspiration in the the Yarlung Zangbo River basin, and there are relatively few studies on the evaluation and fusion of potential evapotranspiration remote sensing products. Therefore, with the Yarlung Zangbo River basin as the research area, the multi-source remote sensing datas are used to fuse a set of potential evapotranspiration fusion data with better adaptability, in order to reveal the potential evapotranspiration changes in the Yarlung Zangbo River basin, and provide a scientific basis for the study of water and heat cycle and ecological hydrological processes of the basin under global climate change.Based on the evaporation pan datas observed by the the Yarlung Zangbo River basin meteorological station from 2001 to 2018, Pearson correlation coefficient, bias and root mean square error were selected to analyze and evaluate four commonly used remote sensing potential evapotranspiration products GLEAM, MOD16A2, GLDAS_Noah and ERA5. Then, a better adaptive potential evapotranspiration fusion data was generated by Triple Collocation (TC) method and least square method, and the spatiotemporal distribution of potential evapotranspiration in the study area was discussed. At site scale and basin scale, ERA5 potential evapotranspiration products had good adaptability in the Yarlung Zangbo River, and its assessment accuracy was significantly better than GLEAM, MOD16A2 and GLDAS_Noah potential evapotranspiration products. In terms of spatial distribution of station accuracy, except GLEAM, the correlation of the other three remote sensing data was most significant in the middle reaches of the basin. The relative deviation of MOD16A2 and ERA5 was small, and the spatial distribution of their root mean square error of the two was opposite to the relative deviation. The weights of MOD16A2, GLDAS_Noah and ERA5 remote sensing datas in the fused data were 31.12%, 30.64% and 38.24%, respectively. The uncertainty analysis of the three remote sensing products showed that the spatial distribution of errors in the upper reaches of the Yarlung Zangbo River basin was gradually decreasing from north to south, but the spatial distribution of errors in other parts was different. The spatial distribution of weights was basically opposite to the spatial distribution of errors. The four types of data had large multi-year mean potential evapotranspiration in the middle of the Yarlung Zangbo River basin, and the difference was whether there was a greater potential evapotranspiration in the southeast corner of the basin. The multi-year average potential evapotranspiration was in the order: ERA5
Abstract:
Artificial recharge of groundwater is a technology that injects excess surface water, rain flood or reclaimed water into the ground through surface infiltration or artificial recharge wells, so as to effectively recharge groundwater and raise the groundwater level. The physical clogging dominated by particle clogging is the main factor restricting the large-scale popularization and application of groundwater artificial recharge project. The particle deposition process in the pores of the media controls the particle clogging phenomenon of the whole media. At present, the research on the internal relationship, mutual transformation and cross-scale coupling between the two processes is limited. The movement and deposition of particles in the pores of the media are the microscopic mechanism of particle clogging. The important factor affecting the movement state of particles in the pores of the media is the pore water flow field. The recharge head is the decisive factor to determine the flow velocity and flow field distribution. The temperature will change the dynamic viscosity and density of the water, which will affect the flow field, change the fluid drag force on the particles and affect the particle deposition. The pH and ionic strength of recharge water affect the particle deposition by affecting the charge of the particles in the water.A physical experimental system of particle clogging in one-dimensional sand column groundwater recharge with fixed head was built, and two media were used for comparative experiments. Combined with physical experiments and Computed Tomography, a numerical model that can describe the particle deposition process in the pores of porous media is constructed, and the numerical model is corrected and verified by physical experiment data and CT scan results. The recharge temperature is selected as the thermodynamic factor, the recharge particle charge is selected as the electrochemical factor, and the recharge head is selected as the engineering factor, and the three are included in one groundwater recharge particle clogging evaluation system. The numerical simulation of multi-physical scenarios with μm-level accuracy was carried out to research the effects of hydraulic factors, thermodynamic factors, and electrochemical factors on the deposition of groundwater recharge particles. According to the combination of the upper limit, the lower limit and the intermediate value of each influencing factor, multiple physical scenarios are set up.The influence weight value of the recharge head on the particle deposition of the two media is 0.144 3, the influence weight value of the recharge temperature is 0.648 8, and the weight value of the recharge particle charge is 0.206 9. There are many data fluctuations in the numerical simulation process, which indicates that the internal flow field and particle motion process of the media are extremely complex and changeable, and a theoretical explanation is proposed. The recharge head is used as a control group to analyze the influence of thermodynamic factors and electrochemical factors on particle clogging and particle deposition in groundwater recharge compared with conventional engineering factors. The range of values is small. In the practice of groundwater artificial recharge engineering, the engineering factors such as recharge head and particle concentration of recharge water still have the greatest impact on particle clogging. The recharge temperature has the highest weight only in engineering scenarios involving extreme water temperature recharge such as groundwater source heat pump.In the case of large variation of recharge temperature, the highest weight factor affecting particle deposition in quartz sand media and glass bead media is recharge temperature, followed by recharge head, and recharge particle charge is the factor with the lowest weight. In the engineering scenarios involving extreme recharge temperature such as ground source heat pump, it is necessary to consider the recharge temperature as an important factor affecting the groundwater recharge clogging. At the same time, the influence of water temperature on the occurrence and development of particle clogging can not be ignored in ordinary projects that do not involve extreme recharge temperature. The influence of electrochemical factors on particle deposition and particle clogging in the process of artificial recharge of groundwater is low. When considering the physical clogging of groundwater recharge such as particle clogging, the electrochemical factors such as ionic strength and pH of recharge water can be selectively ignored.
Artificial recharge of groundwater is a technology that injects excess surface water, rain flood or reclaimed water into the ground through surface infiltration or artificial recharge wells, so as to effectively recharge groundwater and raise the groundwater level. The physical clogging dominated by particle clogging is the main factor restricting the large-scale popularization and application of groundwater artificial recharge project. The particle deposition process in the pores of the media controls the particle clogging phenomenon of the whole media. At present, the research on the internal relationship, mutual transformation and cross-scale coupling between the two processes is limited. The movement and deposition of particles in the pores of the media are the microscopic mechanism of particle clogging. The important factor affecting the movement state of particles in the pores of the media is the pore water flow field. The recharge head is the decisive factor to determine the flow velocity and flow field distribution. The temperature will change the dynamic viscosity and density of the water, which will affect the flow field, change the fluid drag force on the particles and affect the particle deposition. The pH and ionic strength of recharge water affect the particle deposition by affecting the charge of the particles in the water.A physical experimental system of particle clogging in one-dimensional sand column groundwater recharge with fixed head was built, and two media were used for comparative experiments. Combined with physical experiments and Computed Tomography, a numerical model that can describe the particle deposition process in the pores of porous media is constructed, and the numerical model is corrected and verified by physical experiment data and CT scan results. The recharge temperature is selected as the thermodynamic factor, the recharge particle charge is selected as the electrochemical factor, and the recharge head is selected as the engineering factor, and the three are included in one groundwater recharge particle clogging evaluation system. The numerical simulation of multi-physical scenarios with μm-level accuracy was carried out to research the effects of hydraulic factors, thermodynamic factors, and electrochemical factors on the deposition of groundwater recharge particles. According to the combination of the upper limit, the lower limit and the intermediate value of each influencing factor, multiple physical scenarios are set up.The influence weight value of the recharge head on the particle deposition of the two media is 0.144 3, the influence weight value of the recharge temperature is 0.648 8, and the weight value of the recharge particle charge is 0.206 9. There are many data fluctuations in the numerical simulation process, which indicates that the internal flow field and particle motion process of the media are extremely complex and changeable, and a theoretical explanation is proposed. The recharge head is used as a control group to analyze the influence of thermodynamic factors and electrochemical factors on particle clogging and particle deposition in groundwater recharge compared with conventional engineering factors. The range of values is small. In the practice of groundwater artificial recharge engineering, the engineering factors such as recharge head and particle concentration of recharge water still have the greatest impact on particle clogging. The recharge temperature has the highest weight only in engineering scenarios involving extreme water temperature recharge such as groundwater source heat pump.In the case of large variation of recharge temperature, the highest weight factor affecting particle deposition in quartz sand media and glass bead media is recharge temperature, followed by recharge head, and recharge particle charge is the factor with the lowest weight. In the engineering scenarios involving extreme recharge temperature such as ground source heat pump, it is necessary to consider the recharge temperature as an important factor affecting the groundwater recharge clogging. At the same time, the influence of water temperature on the occurrence and development of particle clogging can not be ignored in ordinary projects that do not involve extreme recharge temperature. The influence of electrochemical factors on particle deposition and particle clogging in the process of artificial recharge of groundwater is low. When considering the physical clogging of groundwater recharge such as particle clogging, the electrochemical factors such as ionic strength and pH of recharge water can be selectively ignored.
Abstract:
Runoff is one of the most important water resources in the watershed and is critical to the natural ecosystem. The Han River basin, as an important representative basin of the national "Yangtze River Economic Belt", is one of the water sources of China's South-to-North Water Transfers Project in the upper reaches, and the middle and lower reaches of the Han River are also the main industrial and agricultural production concentration areas in China. Water resources, which constitute one of the demand conditions for industry and agriculture in the region and one of the major constraints on the scale of socio-economic development, are extremely important for regional economic development. Therefore, the impact of vegetation changes on runoff changes under the influence of human activities is conducive to the sustainable development of the Yangtze River basin economy and the protection of the ecological environment to provide a scientific reference basis for research. Based on the meteorological and hydrological data and normalized difference vegetation index (INDV) data of the Han River basin, the impact degree of different factors on the vegetation change of the Han River basin were quantitatively computed using multiple linear regression analysis method, then the impact degree of vegetation variation on discharge change was quantitatively calculated by an adjusted Budyko equation and elastic coefficient method. The Pettitt mutation test identified the mutation year for runoff in the Han River basin in 1991. The amount of runoff change due to each type of driver was calculated separately by the values of annual mean P,ET0,INDV and coefficient ω in the base and change periods, using the elasticity coefficients obtained. Comparing the baseline and mutation periods, it was found that the mean annual reference evapotranspiration in the mutation period increased by 53.59 mm, runoff depth decreased by 119.80 mm, precipitation decreased by 76.31 mm, the subsurface parameter increased by 0.27, and the INDV increased by 0.03 compared to the baseline period. It shows that the subsurface of the Han River basin has been affected by human activities and has undergone significant changes. The annual mean INDV in the Han River basin showed a significant fluctuating growth trend from 1982 to 2015 (p<0.01). The spatial heterogeneity was relatively obvious, and the areas with significant vegetation growth were mainly dominated by the middle and lower reaches. Among them, climatic conditions and anthropogenic factors contributed positively to the increase of INDV, with contribution rates of 99.56% and 0.44%, respectively, but the spatial and temporal distributions of the contribution rates of the two influencing factors were significantly different. In contrast, there is a strong correlation between the subsurface parameter ω and INDV in the Han River basin, indicating that the flow production performance of the basin is highly sensitive to vegetation changes. The contribution rates of vegetation changes caused by climate factors and vegetation changes caused by human factors to runoff were 62.44% and 0.28%, respectively, indicating that vegetation growth caused by climate factors wae one of the important factors leading to the reduction of water resources in the Han River. Therefore, great importance should be attached to the problem of vegetation growth leading to the reduction of water resources in Han River basin.
Runoff is one of the most important water resources in the watershed and is critical to the natural ecosystem. The Han River basin, as an important representative basin of the national "Yangtze River Economic Belt", is one of the water sources of China's South-to-North Water Transfers Project in the upper reaches, and the middle and lower reaches of the Han River are also the main industrial and agricultural production concentration areas in China. Water resources, which constitute one of the demand conditions for industry and agriculture in the region and one of the major constraints on the scale of socio-economic development, are extremely important for regional economic development. Therefore, the impact of vegetation changes on runoff changes under the influence of human activities is conducive to the sustainable development of the Yangtze River basin economy and the protection of the ecological environment to provide a scientific reference basis for research. Based on the meteorological and hydrological data and normalized difference vegetation index (INDV) data of the Han River basin, the impact degree of different factors on the vegetation change of the Han River basin were quantitatively computed using multiple linear regression analysis method, then the impact degree of vegetation variation on discharge change was quantitatively calculated by an adjusted Budyko equation and elastic coefficient method. The Pettitt mutation test identified the mutation year for runoff in the Han River basin in 1991. The amount of runoff change due to each type of driver was calculated separately by the values of annual mean P,ET0,INDV and coefficient ω in the base and change periods, using the elasticity coefficients obtained. Comparing the baseline and mutation periods, it was found that the mean annual reference evapotranspiration in the mutation period increased by 53.59 mm, runoff depth decreased by 119.80 mm, precipitation decreased by 76.31 mm, the subsurface parameter increased by 0.27, and the INDV increased by 0.03 compared to the baseline period. It shows that the subsurface of the Han River basin has been affected by human activities and has undergone significant changes. The annual mean INDV in the Han River basin showed a significant fluctuating growth trend from 1982 to 2015 (p<0.01). The spatial heterogeneity was relatively obvious, and the areas with significant vegetation growth were mainly dominated by the middle and lower reaches. Among them, climatic conditions and anthropogenic factors contributed positively to the increase of INDV, with contribution rates of 99.56% and 0.44%, respectively, but the spatial and temporal distributions of the contribution rates of the two influencing factors were significantly different. In contrast, there is a strong correlation between the subsurface parameter ω and INDV in the Han River basin, indicating that the flow production performance of the basin is highly sensitive to vegetation changes. The contribution rates of vegetation changes caused by climate factors and vegetation changes caused by human factors to runoff were 62.44% and 0.28%, respectively, indicating that vegetation growth caused by climate factors wae one of the important factors leading to the reduction of water resources in the Han River. Therefore, great importance should be attached to the problem of vegetation growth leading to the reduction of water resources in Han River basin.
Abstract:
Over the years, great progress was made in the study of δ(D) and δ(18O) in the Qinghai-Tibet Plateau. However, a comprehensive systematic study of the entire Qinghai-Tibet Plateau was lacking, and much of the research focused on the spatial and temporal patterns and evolutionary mechanisms of precipitation stable isotopes. There was a lack of systematic research at the basin scale for runoff source analysis, and further exploration was needed on the relationships between different runoff components.The available data was used to analyze the δ(D) and δ(18O) values of different types of water samples on the Qinghai-Tibet Plateau to investigate their characteristics. Hydrogen and oxygen stable isotopic data were obtained mainly from the following aspects: (1) Water samples were collected in the Naqu River basin from August 2016 to June 2023, and the stable isotope values of hydrogen and oxygen were measured; (2) Global Network of Isotope in Precipitation (GNIP; https://www.iaea.org/services/networks/gnip); (3) National Qinghai-Tibet Plateau / Third Pole Environment Data Center (TPDC; https://data.tpdc.ac.cn); (4) Stable isotope values of hydrogen and oxygen in the Qinghai-Tibet Plateau studied by predecessors. Water samples collected in the Naqu River basin were analyzed and tested using the L2130-i Water Isotope Analyzer (Picarro, USA), which indicated the stable isotope ratio with respect to the Vienna Standard Mean Ocean Water (V-SMOW). The Local Meteoric Water Line (LMWL) was δ(D)=8.25δ(18O)+16.85. The δ(18O) value increased from February to May and decreased from May to October. A high deuterium surplus value was observed in winter, while it was low in summer. An "inverse altitude effect" was demonstrated by the stable isotopes in the northern part of the Qinghai-Tibet Plateau, while other areas exhibited an obvious "altitude effect". When comparing with the local atmospheric precipitation line and the global atmospheric precipitation line, it was found that both the slope and intercept of the river water line of the Minjiang River and the Daqu-Xianshui River were larger, while the slope of the river water line of the remaining basins was smaller. The Lake Water Line was represented by the equation δ(D)=6.12δ(18O）?23.29, and the Groundwater Line was represented by the equation δ(D)=9.45δ(18O)+28.25. In the isotopic composition of different water bodies on the Qinghai-Tibet Plateau,δ(D) varied from ?212.21‰ to 60.10‰ with a range of 272.31‰ and an average of ?85.80‰,δ(18O) varied from ?36.86‰ to 6.9‰ with a range of 43.76‰ and an average of ?11.71‰. Therefore,δ (18O) was more stable than δ(D) on the Qinghai-Tibet Plateau. The D-excess varied from ?78.55‰ to 41.84‰, with a range of 120.39‰ and an average of 0.95‰. Among all water bodies, the average value of D-excess followed the order: river water > groundwater > lake water > precipitation. The δ(18O) value of Naqu River basin and Daqu-Xianshui River basin in the Qinghai-Tibet Plateau increased first and then decreased along the river channel, the δ(18O) value of Shule River basin and Lhasa River basin decreased along the river channel, and the δ(18O) value of Minjiang River basin increased along the river channel. The Naqu River basin was primarily influenced by lake regulation, while the Shule River basin and the Minjiang River basin located near the Longmen Mountains were primarily affected by evaporation. On the other hand, the Daqu-Xianshuihe River basin and the Lhasa River basin were primarily influenced by atmospheric precipitation recharge. The characteristics of stable isotopes of hydrogen and oxygen varied among different types of water samples. The river water and groundwater were minimally influenced by evaporation, exhibited a close hydraulic relationship, and had a mutual recharge relationship. Precipitation was the main source of water supply in the Lhasa River basin. The average contribution rates of precipitation and groundwater to the water supply in the Shule River basin were similar. The Minjiang River basin was dominated by groundwater recharge. In the upper reaches of the Cuona Lake in the Naqu River basin, precipitation was the main source of water supply, while in the lower reaches, it was mainly from lake water recharge. As the distance increased, the contribution rate of lake water decreased.
Over the years, great progress was made in the study of δ(D) and δ(18O) in the Qinghai-Tibet Plateau. However, a comprehensive systematic study of the entire Qinghai-Tibet Plateau was lacking, and much of the research focused on the spatial and temporal patterns and evolutionary mechanisms of precipitation stable isotopes. There was a lack of systematic research at the basin scale for runoff source analysis, and further exploration was needed on the relationships between different runoff components.The available data was used to analyze the δ(D) and δ(18O) values of different types of water samples on the Qinghai-Tibet Plateau to investigate their characteristics. Hydrogen and oxygen stable isotopic data were obtained mainly from the following aspects: (1) Water samples were collected in the Naqu River basin from August 2016 to June 2023, and the stable isotope values of hydrogen and oxygen were measured; (2) Global Network of Isotope in Precipitation (GNIP; https://www.iaea.org/services/networks/gnip); (3) National Qinghai-Tibet Plateau / Third Pole Environment Data Center (TPDC; https://data.tpdc.ac.cn); (4) Stable isotope values of hydrogen and oxygen in the Qinghai-Tibet Plateau studied by predecessors. Water samples collected in the Naqu River basin were analyzed and tested using the L2130-i Water Isotope Analyzer (Picarro, USA), which indicated the stable isotope ratio with respect to the Vienna Standard Mean Ocean Water (V-SMOW). The Local Meteoric Water Line (LMWL) was δ(D)=8.25δ(18O)+16.85. The δ(18O) value increased from February to May and decreased from May to October. A high deuterium surplus value was observed in winter, while it was low in summer. An "inverse altitude effect" was demonstrated by the stable isotopes in the northern part of the Qinghai-Tibet Plateau, while other areas exhibited an obvious "altitude effect". When comparing with the local atmospheric precipitation line and the global atmospheric precipitation line, it was found that both the slope and intercept of the river water line of the Minjiang River and the Daqu-Xianshui River were larger, while the slope of the river water line of the remaining basins was smaller. The Lake Water Line was represented by the equation δ(D)=6.12δ(18O）?23.29, and the Groundwater Line was represented by the equation δ(D)=9.45δ(18O)+28.25. In the isotopic composition of different water bodies on the Qinghai-Tibet Plateau,δ(D) varied from ?212.21‰ to 60.10‰ with a range of 272.31‰ and an average of ?85.80‰,δ(18O) varied from ?36.86‰ to 6.9‰ with a range of 43.76‰ and an average of ?11.71‰. Therefore,δ (18O) was more stable than δ(D) on the Qinghai-Tibet Plateau. The D-excess varied from ?78.55‰ to 41.84‰, with a range of 120.39‰ and an average of 0.95‰. Among all water bodies, the average value of D-excess followed the order: river water > groundwater > lake water > precipitation. The δ(18O) value of Naqu River basin and Daqu-Xianshui River basin in the Qinghai-Tibet Plateau increased first and then decreased along the river channel, the δ(18O) value of Shule River basin and Lhasa River basin decreased along the river channel, and the δ(18O) value of Minjiang River basin increased along the river channel. The Naqu River basin was primarily influenced by lake regulation, while the Shule River basin and the Minjiang River basin located near the Longmen Mountains were primarily affected by evaporation. On the other hand, the Daqu-Xianshuihe River basin and the Lhasa River basin were primarily influenced by atmospheric precipitation recharge. The characteristics of stable isotopes of hydrogen and oxygen varied among different types of water samples. The river water and groundwater were minimally influenced by evaporation, exhibited a close hydraulic relationship, and had a mutual recharge relationship. Precipitation was the main source of water supply in the Lhasa River basin. The average contribution rates of precipitation and groundwater to the water supply in the Shule River basin were similar. The Minjiang River basin was dominated by groundwater recharge. In the upper reaches of the Cuona Lake in the Naqu River basin, precipitation was the main source of water supply, while in the lower reaches, it was mainly from lake water recharge. As the distance increased, the contribution rate of lake water decreased.
Abstract:
In recent years, extreme weather such as drought and floods have occurred more frequently, and the study of watershed water cycle under changing environments is of great research significance. However, the construction of hydrological and meteorological stations in some regions of the world is not perfect enough, and the consistency of hydrological data in some regions is also disrupted due to changes in underlying surface and climate. These have led to lack of data in many study areas, posing a great obstacle to watershed hydrological simulation. As a multinational basin, the research data in the study area is difficult to fully obtain, which leads to similar difficulties in hydrological simulation of cross-border watersheds as in hydrological simulation of areas lacking data. A set of hydrological research methods suitable for regions lacking data in cross-border watersheds are aimed to be explored.The research method was mainly based on hydrological model and watershed similarity theory. Meteorological data, as an important input data for hydrological simulation, is often difficult to fully obtain in areas without data. Reanalysis data CMADS as a supplement to meteorological data in the hydrological simulation of the Red River basin was selected and its applicability in the Red River basin was studied. Based on the SWAT model and watershed elevation data, the Red River basin was divided into 123 sub watersheds. Then, a series of indicators such as elevation, slope, shape coefficient, forest coverage, precipitation and evapotranspiration were introduced to analyze the similarity of 123 sub watersheds by using of principal component analysis. According to existing little hydrological data and similarity results, four groups of similar watersheds were divided. Model parameters were well calibrated and validated in the basins with enough data, and then the validated parameters were used to drive the hydrological model in the data-shortage basins. The research results were as follows: In the Red River basin, the SWAT model was driven by both traditional meteorological station data and CMADS. Results showed that the CMADS-driven model performed well in the Son Tay station in both the calibration and validation periods, with the ERSR≤0.50 and ENS>0.75. Compared with the results of the CMADS-driven model, the model driven by traditional meteorological station data still satisfied simulation accuracy requirements, but the PBIAS was 12.1% in the calibration period and as high as 21% in the validation period, indicating a large simulation error. This indicated that CMADS could greatly enrich meteorological data in the Red River basin. Based on the results of basin similarity analysis and parameters transplantation, hydrological modeling in data-scarce sub-basins were carried out, which improved the simulation accuracy in most data-scarce sub-basins. Among them,ENS increased from 0.69 to 0.75 for sub-basin 77 after parameter transplantation from sub-basin 123,ENS increased from 0.75 to 0.85 for sub-basin 95 after parameter transplantation from sub-basin 123,ENS increased from 0.64 to 0.78 for sub-basin 96 after parameter transplantation from sub-basin 108, and ENS increased from 0.62 to 0.67 for sub-basin 102 after parameter transplantation from sub-basin 115. This indicated that parameter transplantation based on basin similarity could provide suitable parameters for hydrological models in data-scarce basins and provide more possibilities for hydrological simulation in data-scarce areas. The main conclusions were summarized as follows: Firstly, under the condition of lack of meteorological data, CMADS could be the alternative data for the SWAT model simulation. Compared with simulation results obtained by traditional meteorological station data, the results obtained by the CMADS-driven model could reach a very good standard in both the calibration and validation periods. Secondly, parameter transplantation based on basin similarity can provide suitable parameters for hydrological models in data-scarce areas, and basin similarity method improved the simulation results of most data-scarce sub-basins after parameter transplantation between similar basins. Finally, one research method was put forward successfully, which provide more possibilities for hydrological simulation in more data-scarce areas.
In recent years, extreme weather such as drought and floods have occurred more frequently, and the study of watershed water cycle under changing environments is of great research significance. However, the construction of hydrological and meteorological stations in some regions of the world is not perfect enough, and the consistency of hydrological data in some regions is also disrupted due to changes in underlying surface and climate. These have led to lack of data in many study areas, posing a great obstacle to watershed hydrological simulation. As a multinational basin, the research data in the study area is difficult to fully obtain, which leads to similar difficulties in hydrological simulation of cross-border watersheds as in hydrological simulation of areas lacking data. A set of hydrological research methods suitable for regions lacking data in cross-border watersheds are aimed to be explored.The research method was mainly based on hydrological model and watershed similarity theory. Meteorological data, as an important input data for hydrological simulation, is often difficult to fully obtain in areas without data. Reanalysis data CMADS as a supplement to meteorological data in the hydrological simulation of the Red River basin was selected and its applicability in the Red River basin was studied. Based on the SWAT model and watershed elevation data, the Red River basin was divided into 123 sub watersheds. Then, a series of indicators such as elevation, slope, shape coefficient, forest coverage, precipitation and evapotranspiration were introduced to analyze the similarity of 123 sub watersheds by using of principal component analysis. According to existing little hydrological data and similarity results, four groups of similar watersheds were divided. Model parameters were well calibrated and validated in the basins with enough data, and then the validated parameters were used to drive the hydrological model in the data-shortage basins. The research results were as follows: In the Red River basin, the SWAT model was driven by both traditional meteorological station data and CMADS. Results showed that the CMADS-driven model performed well in the Son Tay station in both the calibration and validation periods, with the ERSR≤0.50 and ENS>0.75. Compared with the results of the CMADS-driven model, the model driven by traditional meteorological station data still satisfied simulation accuracy requirements, but the PBIAS was 12.1% in the calibration period and as high as 21% in the validation period, indicating a large simulation error. This indicated that CMADS could greatly enrich meteorological data in the Red River basin. Based on the results of basin similarity analysis and parameters transplantation, hydrological modeling in data-scarce sub-basins were carried out, which improved the simulation accuracy in most data-scarce sub-basins. Among them,ENS increased from 0.69 to 0.75 for sub-basin 77 after parameter transplantation from sub-basin 123,ENS increased from 0.75 to 0.85 for sub-basin 95 after parameter transplantation from sub-basin 123,ENS increased from 0.64 to 0.78 for sub-basin 96 after parameter transplantation from sub-basin 108, and ENS increased from 0.62 to 0.67 for sub-basin 102 after parameter transplantation from sub-basin 115. This indicated that parameter transplantation based on basin similarity could provide suitable parameters for hydrological models in data-scarce basins and provide more possibilities for hydrological simulation in data-scarce areas. The main conclusions were summarized as follows: Firstly, under the condition of lack of meteorological data, CMADS could be the alternative data for the SWAT model simulation. Compared with simulation results obtained by traditional meteorological station data, the results obtained by the CMADS-driven model could reach a very good standard in both the calibration and validation periods. Secondly, parameter transplantation based on basin similarity can provide suitable parameters for hydrological models in data-scarce areas, and basin similarity method improved the simulation results of most data-scarce sub-basins after parameter transplantation between similar basins. Finally, one research method was put forward successfully, which provide more possibilities for hydrological simulation in more data-scarce areas.
Abstract:
The global average temperature has risen by 1.09 ℃ over the past century. The increase in temperature leads to an increase in evapotranspiration and atmospheric water vapor content, which causes the rate of the water cycle to accelerate, changing the global pattern of the spatial and temporal distribution of water and heat, thus causing the frequent occurrence of droughts, floods, and other extreme events. The Minjiang River basin is an important water conservation area in the southeast of China, with an average annual precipitation between 1 400 mm and 2 000 mm. But the inter-annual unevenness, inter-seasonal variability, and impulsive intra-seasonal distribution of precipitation, as well as the complexity of geographic distribution, make the basin regional, seasonal dry and wet problems occur frequently. Therefore, it is of great significance to study the characteristics of regional dry and wet evolution for economic and social development and ecological environment construction.Based on the daily precipitation data of 29 meteorological stations in the Minjiang River basin from 1962 to 2021, the standardized precipitation index (SPI), combined with the Mann-Kendall test and Morlet wavelet analysis, were used to analyze the characteristics of spatial and temporal changes of dryness and wetness of the Minjiang River basin under different time scales, and combined with the sea surface temperature anomaly index (SSTA), to investigate the effects of ENSO events on the evolution of dryness and wetness in the Minjiang River.The results showed that the Minjiang River basin showed a non-significant wetting trend at different spatial and temporal scales, with a weak wetting trend in spring, and the basin showed a wet-dry-wet-dry distribution from east to west. The summer SPI changed abruptly after the 1990s, showing a significant wetting trend, with a significant wetting trend in the southeastern part of the basin. In autumn, the drought trend began to intensify after 1995, with a tendency toward aridification in the southern part of the basin. Winter is more prone to extreme wet and dry events than other seasons. Extreme wet and dry events at all levels throughout the basin tended to increase on an annual scale. On the seasonal scale, the four types of wet events were on an increasing trend in summer, while extreme drought, severe drought, and mild drought events were all on an increasing trend in fall and mainly occurred after the 1990s. The SPI of the Minjiang River basin has a short-cycle change pattern of 3-8 a and 11-16 a and a long-cycle change pattern of 20-30 a. During the occurrence of ENSO cold and warm events, the mean value of SPI is ?0.124 and 0.193 respectively, and the correlation coefficients between SPI and the intensity of ENSO cold and warm events are ?0.158 and 0.242 respectively, which indicate that there is a greater possibility of wetness when warm events occur, and a greater possibility of drought when cold events occur. The occurrence of ENSO warm events has a significant effect on the wet and dry of the Minjiang River basin during the same period up to the 4-month lag months of dryness and wetness, and the occurrence of ENSO cold events has a significant effect on the dryness and wetness in the lag of 3-5 months.The Minjiang River basin as a whole shows an insignificant wetting trend, with significant wetting in the summer after the 1990s, a tendency to drought in the fall after 1995, and a greater tendency to extreme wet and dry events in the winter than in other seasons. Spatially, a more significant wetting trend exists in the southeastern portion of the basin. There is an increasing trend of wetting and drying events at all levels throughout the basin, with wetting events occurring more often in the summer and drying events occurring more often in the fall and winter. There is a cycle shift of dry-wet-dry alternation in the Minjiang River basin in the 20-30 a scale range. The dry-wet and ENSO warm and cold events in the Minjiang River basin are most significant at a lag of 1-4 months and 3-5 months, respectively.
The global average temperature has risen by 1.09 ℃ over the past century. The increase in temperature leads to an increase in evapotranspiration and atmospheric water vapor content, which causes the rate of the water cycle to accelerate, changing the global pattern of the spatial and temporal distribution of water and heat, thus causing the frequent occurrence of droughts, floods, and other extreme events. The Minjiang River basin is an important water conservation area in the southeast of China, with an average annual precipitation between 1 400 mm and 2 000 mm. But the inter-annual unevenness, inter-seasonal variability, and impulsive intra-seasonal distribution of precipitation, as well as the complexity of geographic distribution, make the basin regional, seasonal dry and wet problems occur frequently. Therefore, it is of great significance to study the characteristics of regional dry and wet evolution for economic and social development and ecological environment construction.Based on the daily precipitation data of 29 meteorological stations in the Minjiang River basin from 1962 to 2021, the standardized precipitation index (SPI), combined with the Mann-Kendall test and Morlet wavelet analysis, were used to analyze the characteristics of spatial and temporal changes of dryness and wetness of the Minjiang River basin under different time scales, and combined with the sea surface temperature anomaly index (SSTA), to investigate the effects of ENSO events on the evolution of dryness and wetness in the Minjiang River.The results showed that the Minjiang River basin showed a non-significant wetting trend at different spatial and temporal scales, with a weak wetting trend in spring, and the basin showed a wet-dry-wet-dry distribution from east to west. The summer SPI changed abruptly after the 1990s, showing a significant wetting trend, with a significant wetting trend in the southeastern part of the basin. In autumn, the drought trend began to intensify after 1995, with a tendency toward aridification in the southern part of the basin. Winter is more prone to extreme wet and dry events than other seasons. Extreme wet and dry events at all levels throughout the basin tended to increase on an annual scale. On the seasonal scale, the four types of wet events were on an increasing trend in summer, while extreme drought, severe drought, and mild drought events were all on an increasing trend in fall and mainly occurred after the 1990s. The SPI of the Minjiang River basin has a short-cycle change pattern of 3-8 a and 11-16 a and a long-cycle change pattern of 20-30 a. During the occurrence of ENSO cold and warm events, the mean value of SPI is ?0.124 and 0.193 respectively, and the correlation coefficients between SPI and the intensity of ENSO cold and warm events are ?0.158 and 0.242 respectively, which indicate that there is a greater possibility of wetness when warm events occur, and a greater possibility of drought when cold events occur. The occurrence of ENSO warm events has a significant effect on the wet and dry of the Minjiang River basin during the same period up to the 4-month lag months of dryness and wetness, and the occurrence of ENSO cold events has a significant effect on the dryness and wetness in the lag of 3-5 months.The Minjiang River basin as a whole shows an insignificant wetting trend, with significant wetting in the summer after the 1990s, a tendency to drought in the fall after 1995, and a greater tendency to extreme wet and dry events in the winter than in other seasons. Spatially, a more significant wetting trend exists in the southeastern portion of the basin. There is an increasing trend of wetting and drying events at all levels throughout the basin, with wetting events occurring more often in the summer and drying events occurring more often in the fall and winter. There is a cycle shift of dry-wet-dry alternation in the Minjiang River basin in the 20-30 a scale range. The dry-wet and ENSO warm and cold events in the Minjiang River basin are most significant at a lag of 1-4 months and 3-5 months, respectively.
Abstract:
The Western Route of the South-to-North Water Transfers Project represents a vital strategic initiative aiming at alleviating water scarcity in the Yellow River basin and northern China. Despite being in the planning and evaluation phase, establishing ecologically sustainable flow targets for rivers in the water source area remains a critical and challenging aspect of water diversion planning. In recent years, researchers have utilized the sensitive responses of benthic macroinvertebrates to hydrological conditions as indicators for determining ecological flow targets. However, there has been limited investigation into benthic macroinvertebrates in the water source area of the Western Route Project, with only a few studies conducted in distant locations such as the Yalong River and Dadu River, far from the proposed dam sites. To address this gap and explore the community structure of benthic macroinvertebrates while identifying suitable hydrological conditions in this region, two extensive surveys were conducted during both flood and non-flood seasons in 2022. Variations in benthic macroinvertebrate biological indices under different flow rates and water depths was analyzed using one-way analysis of variance and canonical correspondence analysis. Additionally, the research assessed the relationships between dominant benthic macroinvertebrate species and hydrological factors, determining optimal hydrological conditions and suitable ranges for dominant species using weighted averaging. Significant differences between optimal values and mean values of habitat factors were determined through a two-tailed t-test, while habitat suitability curves for dominant species were constructed using habitat simulation methods. The results revealed the presence of 50 genera of benthic macroinvertebrates in the two surveys, with the classInsecta
dominating the community, constituting 90.20% of the total taxon. The dominant species varied temporally, with
Heptageniidae sp.
dominating during the flood season （
Y
=19.9%）, and
Perlidae sp.
dominating during the non-flood season （
Y
=13.8%）. Temporally, higher biological density was observed during the flood season, while higher biodiversity and species evenness were noted during the non-flood season. Spatially, biodiversity and biological density were significantly higher in the upper-route of the diversion project compared to the lower-route. Significant differences in species richness and the Margalef diversity index were observed among different velocity intervals within the 0-1.0 m/s range, with the highest number of species and various biodiversity indices found in the 0.5 to 1.0 m/s range during both flood and non-flood periods. Similarly, significant differences in biomass were observed between different depth intervals within the 0-0.6 m range, with the highest benthic macroinvertebrate density recorded in the 0-0.2 m interval. Targeting seven dominant species in the water source area, suitable hydrological conditions were determined to be a water depth of 0.2-0.4 m and flow velocity of 0.3-0.6 m/s using habitat suitability simulation methods.
In conclusion, during the survey period, 50 genera of benthic macroinvertebrates were recorded in the water source area of the Western Route Project, with
Insecta
being the dominant group, particularly
Heptageniidae sp
. during the flood season and
Perlidae sp.
during the non-flood season. Temporally, higher biological diversity and species evenness were observed during the non-flood season, emphasizing the importance of ecological base flow protection during this period to maintain river biodiversity. Spatially, benthic biological diversity and density were higher in the upper scheme water diversion sections compared to the lower scheme water diversion sections. The recommended suitable ranges for water depth and flow velocity for dominant species of large benthic animals in the water source area rivers were determined to be 0.2-0.4 m and 0.3-0.6 m/s, respectively. These findings can contribute valuable insights for simulating and evaluating suitable habitats for benthic animals in the water source area of the Western Route Project.
The Western Route of the South-to-North Water Transfers Project represents a vital strategic initiative aiming at alleviating water scarcity in the Yellow River basin and northern China. Despite being in the planning and evaluation phase, establishing ecologically sustainable flow targets for rivers in the water source area remains a critical and challenging aspect of water diversion planning. In recent years, researchers have utilized the sensitive responses of benthic macroinvertebrates to hydrological conditions as indicators for determining ecological flow targets. However, there has been limited investigation into benthic macroinvertebrates in the water source area of the Western Route Project, with only a few studies conducted in distant locations such as the Yalong River and Dadu River, far from the proposed dam sites. To address this gap and explore the community structure of benthic macroinvertebrates while identifying suitable hydrological conditions in this region, two extensive surveys were conducted during both flood and non-flood seasons in 2022. Variations in benthic macroinvertebrate biological indices under different flow rates and water depths was analyzed using one-way analysis of variance and canonical correspondence analysis. Additionally, the research assessed the relationships between dominant benthic macroinvertebrate species and hydrological factors, determining optimal hydrological conditions and suitable ranges for dominant species using weighted averaging. Significant differences between optimal values and mean values of habitat factors were determined through a two-tailed t-test, while habitat suitability curves for dominant species were constructed using habitat simulation methods. The results revealed the presence of 50 genera of benthic macroinvertebrates in the two surveys, with the class
Abstract:
The phase I of the Eastern Route of the South-to-North Water Transfers Project (hereinafter referred to as Phase I) is an important part of the South-to-North Water Transfers Project and the backbone project of the national water network. Under the background of the current ecological civilization construction, the eco-environmental benefits of the receiving area of the project are widely concerned. Phase I has been in operation for nearly 10 years. As of the end of June 2023, a total of 6.139 billion m3 of water has been transferred to Shandong, which has brought remarkable benefits. So, scientific analysis of the eco-environmental evolution of phase I is conducive to the high-quality promotion of subsequent projects and the high-quality development of economy and society. To analyze the evolution characteristics of eco-environmental of the phase I, the role of phase I is analyzed in optimizing water resources allocation, ensuring drinking water safety for the masses, reviving the eco-environment of rivers and lakes, and smoothing the North-South economic cycle by combining qualitative and quantitative methods. The indicators, such as annual water supply, water quality improvement, ecological replenishment, groundwater pressure recovery, groundwater level, water area, green area, water conservation, were selected, and the eco-environmental benefit evaluation indicator system of the phase I was established. On this basis, the eco-environmental evolution analysis method of the phase I was established based on VIKOR compromise solution ranking method, considering the incongruity between multiple indicators. The constructed evaluation indicator system and evolution analysis method are applied to calculate and analyze the evolution situation of eco-environmental benefits of the phase I from 2013 to 2022. The results show that: The overall benefits have been gradually increasing since the opening of water supply, reaching a peak in 2020, and then basically stabilizing. The phase I has promoted the recovery of underground water pressure, water level, the pollution control and water quality protection along the route have also effectively improved the water quality of rivers and lakes, which have improved the eco-environment along the route. The phase I has produced sustained benefits in water resources protection and water ecological restoration, and is expected to achieve a steady equilibrium mechanism. The ranking value remained above 0.8 in the past three years; Affected by factors such as dry precipitation, which in turn affected groundwater extraction and groundwater level, indirect eco-environmental benefits decreased by 29.2% in 2019, and then quickly recovered and remained stable. Based on the analysis of the evolution of direct and indirect benefits, the corresponding improvement strategies are proposed from the aspects of improving quality and efficiency, ensuring water quality and evaluating mechanism construction, in order to provide references for eco-environment evaluation of the Eastern Route project and relevant research and decision-making on high-quality development. The constructed indicator system of eco-environmental of the phase I based on the analysis of the actual benefits from two dimensions of direct and indirect benefits is more targeted and operable. VIKOR method is adopted to analyze the evolutionary situation of eco-environmental of the phase I from 2013 to 2022, which can better clarify the main constraints of the improvement of eco-environmental in the current state. The eco-environmental of the phase I have basically shown a steady improvement since the water operation, but have declined to a certain extent after 2020. It should be pointed out that the improvement of the eco-environment along the phase I is the common result of the efforts of all parties under the background of ecological civilization construction and harmonious coexistence between human and nature. The water provided by the phase I is an important factor for the improvement of the eco-environment along the route, but it is not the only factor. When evaluating the ecological benefits of the phase I, how to clarify which eco-environment improvement is caused by the increase in water supply of the Eastern Route project, accurately calculate and analyze the ecological benefits of the phase I by selecting a reasonable indicator system, and evaluate and predict the development and change trend of the ecological benefits are difficulties worthy of further research and exploration.
The phase I of the Eastern Route of the South-to-North Water Transfers Project (hereinafter referred to as Phase I) is an important part of the South-to-North Water Transfers Project and the backbone project of the national water network. Under the background of the current ecological civilization construction, the eco-environmental benefits of the receiving area of the project are widely concerned. Phase I has been in operation for nearly 10 years. As of the end of June 2023, a total of 6.139 billion m3 of water has been transferred to Shandong, which has brought remarkable benefits. So, scientific analysis of the eco-environmental evolution of phase I is conducive to the high-quality promotion of subsequent projects and the high-quality development of economy and society. To analyze the evolution characteristics of eco-environmental of the phase I, the role of phase I is analyzed in optimizing water resources allocation, ensuring drinking water safety for the masses, reviving the eco-environment of rivers and lakes, and smoothing the North-South economic cycle by combining qualitative and quantitative methods. The indicators, such as annual water supply, water quality improvement, ecological replenishment, groundwater pressure recovery, groundwater level, water area, green area, water conservation, were selected, and the eco-environmental benefit evaluation indicator system of the phase I was established. On this basis, the eco-environmental evolution analysis method of the phase I was established based on VIKOR compromise solution ranking method, considering the incongruity between multiple indicators. The constructed evaluation indicator system and evolution analysis method are applied to calculate and analyze the evolution situation of eco-environmental benefits of the phase I from 2013 to 2022. The results show that: The overall benefits have been gradually increasing since the opening of water supply, reaching a peak in 2020, and then basically stabilizing. The phase I has promoted the recovery of underground water pressure, water level, the pollution control and water quality protection along the route have also effectively improved the water quality of rivers and lakes, which have improved the eco-environment along the route. The phase I has produced sustained benefits in water resources protection and water ecological restoration, and is expected to achieve a steady equilibrium mechanism. The ranking value remained above 0.8 in the past three years; Affected by factors such as dry precipitation, which in turn affected groundwater extraction and groundwater level, indirect eco-environmental benefits decreased by 29.2% in 2019, and then quickly recovered and remained stable. Based on the analysis of the evolution of direct and indirect benefits, the corresponding improvement strategies are proposed from the aspects of improving quality and efficiency, ensuring water quality and evaluating mechanism construction, in order to provide references for eco-environment evaluation of the Eastern Route project and relevant research and decision-making on high-quality development. The constructed indicator system of eco-environmental of the phase I based on the analysis of the actual benefits from two dimensions of direct and indirect benefits is more targeted and operable. VIKOR method is adopted to analyze the evolutionary situation of eco-environmental of the phase I from 2013 to 2022, which can better clarify the main constraints of the improvement of eco-environmental in the current state. The eco-environmental of the phase I have basically shown a steady improvement since the water operation, but have declined to a certain extent after 2020. It should be pointed out that the improvement of the eco-environment along the phase I is the common result of the efforts of all parties under the background of ecological civilization construction and harmonious coexistence between human and nature. The water provided by the phase I is an important factor for the improvement of the eco-environment along the route, but it is not the only factor. When evaluating the ecological benefits of the phase I, how to clarify which eco-environment improvement is caused by the increase in water supply of the Eastern Route project, accurately calculate and analyze the ecological benefits of the phase I by selecting a reasonable indicator system, and evaluate and predict the development and change trend of the ecological benefits are difficulties worthy of further research and exploration.
Abstract:
Ecological water demand is proposed in the context of the increasing contradiction between human social water use and natural ecosystem water use, which is the basic basis and key to ecological water use control and regional ecological environment restoration, and at the same time, it is also the amount of water needed to ensure the structural integrity of the ecosystem, the normal functioning of the function, and the stability of the ecological process, which can be divided into ecological water demand of the rivers, wetlands, lakes and other ecological water demand. In order to ensure the healthy development of the ecosystem of Qinghai Lake basin and realize the rational allocation of water resources, it aims to provide an important reference basis for the ecological restoration of rivers and water resources management in Qinghai Lake basin. Based on the measured long time series data from 1961 to 2020 at Buhahekou station and Gangcha station of Hydrology and Water Resources Forecast Center of Qinghai Province, the runoff volume was subjected to trend change analysis and runoff mutation test by sliding T-test and Mann-Kendall test, and the data were verified to be suitable for the study of ecological water demand of Qinghai Lake basin through the triple-sex review. The ecological water demand within the channels of the Buha and Shaliu Rivers was calculated using Tennant, the mean flow of the deadliest month in the last 10 years, the mean flow of the month with 90% guarantee rate, and the intra-annual spreading method. The four methods were compared and analysed with the improved Tennant evaluation criteria and satisfaction degree. The calculation results obtained that it is more reasonable to calculate the ecological water demand of Buha River by the method of intra-annual spreading, and it is more reasonable to calculate the ecological water demand of Shaliu River by the method of 90% guaranteed monthly average flow rate. The following conclusions are drawn: The average flow rate method of the deadliest month in the past ten years has consistent monthly changes within the year, which is not in line with the process of abundance and depletion changes within the year, and the calculation results are not in line with the practical requirements. Tennant method in the ecological flow calculation of Buha River and Shaliu River, some months are lower than the range of Tennant minimum evaluation index, and the calculation results do not meet the requirements. In the analysis of comprehensive water demand and ecological water demand satisfaction, the intra-annual spreading method is more representative for calculating the ecological water demand for Buha River, and the monthly average flow rate method with 90% guarantee rate is more representative for calculating the ecological water demand for Shaliu River. The degree of satisfaction of ecological water demand of Buha River in July is low, and the degree of satisfaction of ecological water demand of Shaliu River in February is low. The contradiction between upstream and downstream supply and demand of water resources in that month should be considered to make a more reasonable water resources scheduling. According to the ecological water demand in the channel of Shaliu River calculated by Buha River and 90% guarantee rate monthly average flow method, Buha River has the largest ecological water demand in July, 31.9×108m3, and the smallest ecological water demand in February, 0.86×108m3; Shaliu River has the largest ecological water demand in July, 10.7×108m3, and the smallest ecological water demand in February, 0.14×108m3.
Ecological water demand is proposed in the context of the increasing contradiction between human social water use and natural ecosystem water use, which is the basic basis and key to ecological water use control and regional ecological environment restoration, and at the same time, it is also the amount of water needed to ensure the structural integrity of the ecosystem, the normal functioning of the function, and the stability of the ecological process, which can be divided into ecological water demand of the rivers, wetlands, lakes and other ecological water demand. In order to ensure the healthy development of the ecosystem of Qinghai Lake basin and realize the rational allocation of water resources, it aims to provide an important reference basis for the ecological restoration of rivers and water resources management in Qinghai Lake basin. Based on the measured long time series data from 1961 to 2020 at Buhahekou station and Gangcha station of Hydrology and Water Resources Forecast Center of Qinghai Province, the runoff volume was subjected to trend change analysis and runoff mutation test by sliding T-test and Mann-Kendall test, and the data were verified to be suitable for the study of ecological water demand of Qinghai Lake basin through the triple-sex review. The ecological water demand within the channels of the Buha and Shaliu Rivers was calculated using Tennant, the mean flow of the deadliest month in the last 10 years, the mean flow of the month with 90% guarantee rate, and the intra-annual spreading method. The four methods were compared and analysed with the improved Tennant evaluation criteria and satisfaction degree. The calculation results obtained that it is more reasonable to calculate the ecological water demand of Buha River by the method of intra-annual spreading, and it is more reasonable to calculate the ecological water demand of Shaliu River by the method of 90% guaranteed monthly average flow rate. The following conclusions are drawn: The average flow rate method of the deadliest month in the past ten years has consistent monthly changes within the year, which is not in line with the process of abundance and depletion changes within the year, and the calculation results are not in line with the practical requirements. Tennant method in the ecological flow calculation of Buha River and Shaliu River, some months are lower than the range of Tennant minimum evaluation index, and the calculation results do not meet the requirements. In the analysis of comprehensive water demand and ecological water demand satisfaction, the intra-annual spreading method is more representative for calculating the ecological water demand for Buha River, and the monthly average flow rate method with 90% guarantee rate is more representative for calculating the ecological water demand for Shaliu River. The degree of satisfaction of ecological water demand of Buha River in July is low, and the degree of satisfaction of ecological water demand of Shaliu River in February is low. The contradiction between upstream and downstream supply and demand of water resources in that month should be considered to make a more reasonable water resources scheduling. According to the ecological water demand in the channel of Shaliu River calculated by Buha River and 90% guarantee rate monthly average flow method, Buha River has the largest ecological water demand in July, 31.9×108m3, and the smallest ecological water demand in February, 0.86×108m3; Shaliu River has the largest ecological water demand in July, 10.7×108m3, and the smallest ecological water demand in February, 0.14×108m3.
Abstract:
The ecological environment of the Yellow River basin was fragile, and the natural conditions varied greatly across different regions. This presented significant challenges for the coordinated development of the regional economy. At present, there were still serious ecological problems in the Yellow River, such as water shortages, ecological fragility, and the threat of natural disasters. Most regions of Gansu, Shaanxi, Ningxia, and other provinces and regions were located in arid and semi-arid areas. These areas had a dry climate, receive little rainfall, and had insufficient water resources. As a result, these provinces and region faced significant challenges in achieving both ecological protection and high-quality economic development. In order to promote the social and economic development of the Yellow River water shortage region, the provinces and region of Gansu, Ningxia and Shaanxi had undertaken a series of water irrigation projects with the support of the country. The construction and operation of these projects had greatly contributed to the social and economic development, as well as the ecological improvement, of the water area. However, over time, some secondary problems had also emerged. After completing the project, the adverse natural ecological conditions in the irrigation area were changed, leading to substantial economic and social benefits. However, due to the unsustainable irrigation methods in the area, the groundwater level was rising rapidly, resulting in ecological issues such as secondary soil salinization and the degradation of underground water quality. Therefore, it is significant to conduct a comprehensive benefit analysis and evaluation of the upper reaches of the Yellow River in order to gain an objective understanding of the existing problems and find solutions.The economic benefits of the Jingtaichuan Electric Power Irrigation Project since its construction would be analyzed using time series analysis. Based on the normalized vegetation index data from 2000 to 2020, an analysis was conducted to examine the time and space dynamic changes of the vegetation index in the Jingdian Irrigation Area using Slope trend analysis. The results showed that water transfer increased from 89.37 million m3 in 1973 to 605.77 million m3 in 2020, representing a five-fold increase. Additionally, the newly irrigated area was 911,800 mu. In 1973, power consumption was 18.18 million kW?h, and by 2020, it had increased to 1.00 billion kW?h, representing an increase of nearly 60 times. From 1980 to 2020, per capita net income in rural areas increased by 19,854 yuan. Savings deposits of both urban and rural residents have increased by nearly 100 times. Regional GDP increased by RMB 12.2 billion. Fiscal revenue increased by RMB 578 million yuan, which represented an increase of 289 times in 40 years. The vegetation index continued to increase, and the regional ecology showed significant improvement. The average INDV index reached its highest value of 0.41 in 2019. The windbreak and sand-fixing forest area constructed in the irrigated area reached 38,000 hectares. Moreover, the area showing an improvement in vegetation index has surpassed the degraded area, indicating an overall improvement in the state. The continuous expansion of saline-alkali land area since 1980 could be attributed to long-term, unsustainable irrigation practices and extensive land management. After the completion of the Jingtaichuan Electric Power Irrigation Project, the ecology had been effectively restored, promoting the rapid development of the regional agricultural economy and the continuous improvement of residents' living standards. Overall, irrigation was conducted in the upper reaches of the Yellow River. Although the construction cost was significant, it could yield substantial social, economic, and ecological benefits. This could play a crucial role in harmonizing the relationship between people and the land, as well as promoting ecological protection and economic development.
The ecological environment of the Yellow River basin was fragile, and the natural conditions varied greatly across different regions. This presented significant challenges for the coordinated development of the regional economy. At present, there were still serious ecological problems in the Yellow River, such as water shortages, ecological fragility, and the threat of natural disasters. Most regions of Gansu, Shaanxi, Ningxia, and other provinces and regions were located in arid and semi-arid areas. These areas had a dry climate, receive little rainfall, and had insufficient water resources. As a result, these provinces and region faced significant challenges in achieving both ecological protection and high-quality economic development. In order to promote the social and economic development of the Yellow River water shortage region, the provinces and region of Gansu, Ningxia and Shaanxi had undertaken a series of water irrigation projects with the support of the country. The construction and operation of these projects had greatly contributed to the social and economic development, as well as the ecological improvement, of the water area. However, over time, some secondary problems had also emerged. After completing the project, the adverse natural ecological conditions in the irrigation area were changed, leading to substantial economic and social benefits. However, due to the unsustainable irrigation methods in the area, the groundwater level was rising rapidly, resulting in ecological issues such as secondary soil salinization and the degradation of underground water quality. Therefore, it is significant to conduct a comprehensive benefit analysis and evaluation of the upper reaches of the Yellow River in order to gain an objective understanding of the existing problems and find solutions.The economic benefits of the Jingtaichuan Electric Power Irrigation Project since its construction would be analyzed using time series analysis. Based on the normalized vegetation index data from 2000 to 2020, an analysis was conducted to examine the time and space dynamic changes of the vegetation index in the Jingdian Irrigation Area using Slope trend analysis. The results showed that water transfer increased from 89.37 million m3 in 1973 to 605.77 million m3 in 2020, representing a five-fold increase. Additionally, the newly irrigated area was 911,800 mu. In 1973, power consumption was 18.18 million kW?h, and by 2020, it had increased to 1.00 billion kW?h, representing an increase of nearly 60 times. From 1980 to 2020, per capita net income in rural areas increased by 19,854 yuan. Savings deposits of both urban and rural residents have increased by nearly 100 times. Regional GDP increased by RMB 12.2 billion. Fiscal revenue increased by RMB 578 million yuan, which represented an increase of 289 times in 40 years. The vegetation index continued to increase, and the regional ecology showed significant improvement. The average INDV index reached its highest value of 0.41 in 2019. The windbreak and sand-fixing forest area constructed in the irrigated area reached 38,000 hectares. Moreover, the area showing an improvement in vegetation index has surpassed the degraded area, indicating an overall improvement in the state. The continuous expansion of saline-alkali land area since 1980 could be attributed to long-term, unsustainable irrigation practices and extensive land management. After the completion of the Jingtaichuan Electric Power Irrigation Project, the ecology had been effectively restored, promoting the rapid development of the regional agricultural economy and the continuous improvement of residents' living standards. Overall, irrigation was conducted in the upper reaches of the Yellow River. Although the construction cost was significant, it could yield substantial social, economic, and ecological benefits. This could play a crucial role in harmonizing the relationship between people and the land, as well as promoting ecological protection and economic development.
Abstract:
River systems, particularly plain river systems, are rich in fine-grained sediments, which exhibit a significant adsorption capacity for phosphorus. The fine-grained sediments play a significant role in river water pollution, serving as both sources and sinks for pollutants. The confluence zone is a crucial node for phosphorus transport and deposition in river systems. Due to the complex flow structure in this area, it is difficult to reveal the distribution characteristics of phosphorus on bed sediments at river confluences.An experimental system and detection method were designed to investigate the distribution of phosphorus on bed sediments within the confluence zone. The three-dimensional flow field of the confluence and the total phosphorus content of the bed sediments were measured. Subsequently, the relationship between the flow zone and the spatial distribution of total phosphorus on the bed sediments was analyzed. Based on 204 sets of hydrodynamic parameters and total phosphorus content data obtained from the confluence experiment, an artificial neural network model was established to quantitatively analyze the influence of hydrodynamic parameters within the confluence zone on the total phosphorus content of bed sediments, thereby identifying the key hydrodynamic parameters. The results show that: (1) Under the condition of large confluence ratio (Qr= 0.6), the total phosphorus content of bed sediments in the separation zone and the shear layer zone was high, indicating zones with high occurrences of phosphorus. The total phosphorus content of bed sediments in the acceleration zone was 21.4% lower than that in the separation zone, indicating a zone with low phosphorus occurrence. Under the condition of small confluence ratio (Qr= 0.4), except for sediments in the shear layer zone, which exhibited a high phosphorus content, the other areas exhibited a comparatively low phosphorus content. (2) The low horizontal flow velocity in the separation zone facilitated the migration of phosphorus from the water body to the bed sediments, resulting in a high phosphorus content of the bed sediments. Conversely, the high horizontal flow velocity in the acceleration zone outside the separation zone resulted in a low phosphorus content of the bed sediments. However, there was a significantly high phosphorus content in the local area (shear layer zone) within the acceleration zone, which was attributed to the downward flow (primarily generated by spiral flow) in this area. The downward flow promoted the exchange of surface water and pore water, increasing the contact probability between phosphorus and the bed sediments. (3) An artificial neural network model, formulated using hydrodynamic parameters, has accurately predicted the phosphorus content of the bed sediments at the confluence. Remarkably, the average relative error between the model predictions and the experimental results was only 5.71%. Through parameter sensitivity analysis of the model, it was found that w1 and w2 exerted the most significant influence on the model prediction accuracy, indicating that the vertical velocities in the lower and middle layers were crucial hydrodynamic parameters impacting the total phosphorus content of the bed sediments at the confluence. The horizontal flow velocity is low in the separation zone, resulting in high phosphorus content of the bed sediments. Conversely, in the acceleration zone outside the separation zone, the horizontal flow velocity is higher, leading to lower phosphorus content of the bed sediments. However, there is a notable exception in a specific region of the acceleration zone known as the shear layer zone, where a large amount of phosphorus is present. This phenomenon is related to the downward flow caused by spiral flow in this area, which promotes the exchange of surface water and pore water, increasing the contact probability between phosphorus and bed sediments.
River systems, particularly plain river systems, are rich in fine-grained sediments, which exhibit a significant adsorption capacity for phosphorus. The fine-grained sediments play a significant role in river water pollution, serving as both sources and sinks for pollutants. The confluence zone is a crucial node for phosphorus transport and deposition in river systems. Due to the complex flow structure in this area, it is difficult to reveal the distribution characteristics of phosphorus on bed sediments at river confluences.An experimental system and detection method were designed to investigate the distribution of phosphorus on bed sediments within the confluence zone. The three-dimensional flow field of the confluence and the total phosphorus content of the bed sediments were measured. Subsequently, the relationship between the flow zone and the spatial distribution of total phosphorus on the bed sediments was analyzed. Based on 204 sets of hydrodynamic parameters and total phosphorus content data obtained from the confluence experiment, an artificial neural network model was established to quantitatively analyze the influence of hydrodynamic parameters within the confluence zone on the total phosphorus content of bed sediments, thereby identifying the key hydrodynamic parameters. The results show that: (1) Under the condition of large confluence ratio (Qr= 0.6), the total phosphorus content of bed sediments in the separation zone and the shear layer zone was high, indicating zones with high occurrences of phosphorus. The total phosphorus content of bed sediments in the acceleration zone was 21.4% lower than that in the separation zone, indicating a zone with low phosphorus occurrence. Under the condition of small confluence ratio (Qr= 0.4), except for sediments in the shear layer zone, which exhibited a high phosphorus content, the other areas exhibited a comparatively low phosphorus content. (2) The low horizontal flow velocity in the separation zone facilitated the migration of phosphorus from the water body to the bed sediments, resulting in a high phosphorus content of the bed sediments. Conversely, the high horizontal flow velocity in the acceleration zone outside the separation zone resulted in a low phosphorus content of the bed sediments. However, there was a significantly high phosphorus content in the local area (shear layer zone) within the acceleration zone, which was attributed to the downward flow (primarily generated by spiral flow) in this area. The downward flow promoted the exchange of surface water and pore water, increasing the contact probability between phosphorus and the bed sediments. (3) An artificial neural network model, formulated using hydrodynamic parameters, has accurately predicted the phosphorus content of the bed sediments at the confluence. Remarkably, the average relative error between the model predictions and the experimental results was only 5.71%. Through parameter sensitivity analysis of the model, it was found that w1 and w2 exerted the most significant influence on the model prediction accuracy, indicating that the vertical velocities in the lower and middle layers were crucial hydrodynamic parameters impacting the total phosphorus content of the bed sediments at the confluence. The horizontal flow velocity is low in the separation zone, resulting in high phosphorus content of the bed sediments. Conversely, in the acceleration zone outside the separation zone, the horizontal flow velocity is higher, leading to lower phosphorus content of the bed sediments. However, there is a notable exception in a specific region of the acceleration zone known as the shear layer zone, where a large amount of phosphorus is present. This phenomenon is related to the downward flow caused by spiral flow in this area, which promotes the exchange of surface water and pore water, increasing the contact probability between phosphorus and bed sediments.
Abstract:
Designing flood standard is crucial in the planning, design, and operational management of water resources and hydropower engineering. The determination of the standard is influenced by various factors such as the socio-economic conditions, the population size, and the scale and efficiency of engineering construction. With the intensification of climate change and the advancement of new theories and technologies, the international community began to explore new flood standard selection criteria and climate change adaptation policies to meet the requirements of flood management. Some typical developed countries such as the United States, the Netherlands, the United Kingdom, and Japan had taken a series of measures to address the challenges posed by climate change on the design of extreme rainfall and floods. They had also formulated corresponding policies and standards, which could provide valuable experiences for other countries.The research findings and current application status of flood standard selection and climate change adaptation policies in several typical developed countries, including the United States, the Netherlands, the United Kingdom and Japan, were systematically reviewed. The policy formulation process and standard selection methods of these countries were comprehensively analyzed from two perspectives: engineering design flood standards and basin flood management standards. Moreover, the specific strategies and measures adopted by the United Kingdom and Japan in response to climate change impacts on extreme rainfall and floods were summarized. The main results were as follows:Federal Emergency Management Agency (FEMA) in the United States had proposed multiple methods for determining flood standards, including prescriptive approach, incremental consequence analysis, risk-informed decision making and site-specific PMP studies. It emphasizes the importance of considering flood potential hazards and risks rather than simply relying on dam size. The Netherlands, through a national flood risk analysis, had transitioned its flood safety standards from being based on exceedance probabilities per year to being based on flood risk. Similarly, the United Kingdom has moved away from using components of the Probable Maximum Flood (PMF) in determining flood standards. Instead, it emphasizes considerations related to potential loss of life, setting high design standards accordingly, often no less than a 10,000-year return period for dam projects with such risks. Meanwhile, in Japan, flood standards are determined through a combination of design rainfall and runoff models. The highest standard ranges from 100 to 200 years, with variations influenced by the dam's material, such as earth and rockfill versus concrete. The United Kingdom and Japan had taken proactive measures to establish comprehensive regulations to address climate change, utilizing future climate projection data to determine the magnitude of changes in design rainfall and floods, and incorporating this information into governmental decision-making and planning processes.In summary, the formulation of engineering design flood standards were mainly reviewed in the United States, the Netherlands, the United Kingdom, and Japan. Additionally, the adaptive strategies formulated by the United Kingdom and Japan in response to climate change were also researched. Based on the analysis and summary of experiences from these countries, the following recommendations were proposed. Firstly, research and application of flood standards was strengthened based on modern risk concepts to make them more scientifically sound. Secondly, a dynamic perspective was adopted to determine flood standards more proactively, considering changes in future socio-economic development. Thirdly, a holistic approach was adopted to coordinate and integrate flood standards across different regions to avoid adverse "risk transfer" effects. Finally, long-term future climate projection data was comprehensively utilized to scientifically assess changes in extreme rainfall and floods and formulate adaptive policies to address climate change. These recommendations can provide valuable insights for the formulation of flood management and climate change adaptation strategies in China's new era, promoting sustainable development in water resources and hydropower engineering.
Designing flood standard is crucial in the planning, design, and operational management of water resources and hydropower engineering. The determination of the standard is influenced by various factors such as the socio-economic conditions, the population size, and the scale and efficiency of engineering construction. With the intensification of climate change and the advancement of new theories and technologies, the international community began to explore new flood standard selection criteria and climate change adaptation policies to meet the requirements of flood management. Some typical developed countries such as the United States, the Netherlands, the United Kingdom, and Japan had taken a series of measures to address the challenges posed by climate change on the design of extreme rainfall and floods. They had also formulated corresponding policies and standards, which could provide valuable experiences for other countries.The research findings and current application status of flood standard selection and climate change adaptation policies in several typical developed countries, including the United States, the Netherlands, the United Kingdom and Japan, were systematically reviewed. The policy formulation process and standard selection methods of these countries were comprehensively analyzed from two perspectives: engineering design flood standards and basin flood management standards. Moreover, the specific strategies and measures adopted by the United Kingdom and Japan in response to climate change impacts on extreme rainfall and floods were summarized. The main results were as follows:Federal Emergency Management Agency (FEMA) in the United States had proposed multiple methods for determining flood standards, including prescriptive approach, incremental consequence analysis, risk-informed decision making and site-specific PMP studies. It emphasizes the importance of considering flood potential hazards and risks rather than simply relying on dam size. The Netherlands, through a national flood risk analysis, had transitioned its flood safety standards from being based on exceedance probabilities per year to being based on flood risk. Similarly, the United Kingdom has moved away from using components of the Probable Maximum Flood (PMF) in determining flood standards. Instead, it emphasizes considerations related to potential loss of life, setting high design standards accordingly, often no less than a 10,000-year return period for dam projects with such risks. Meanwhile, in Japan, flood standards are determined through a combination of design rainfall and runoff models. The highest standard ranges from 100 to 200 years, with variations influenced by the dam's material, such as earth and rockfill versus concrete. The United Kingdom and Japan had taken proactive measures to establish comprehensive regulations to address climate change, utilizing future climate projection data to determine the magnitude of changes in design rainfall and floods, and incorporating this information into governmental decision-making and planning processes.In summary, the formulation of engineering design flood standards were mainly reviewed in the United States, the Netherlands, the United Kingdom, and Japan. Additionally, the adaptive strategies formulated by the United Kingdom and Japan in response to climate change were also researched. Based on the analysis and summary of experiences from these countries, the following recommendations were proposed. Firstly, research and application of flood standards was strengthened based on modern risk concepts to make them more scientifically sound. Secondly, a dynamic perspective was adopted to determine flood standards more proactively, considering changes in future socio-economic development. Thirdly, a holistic approach was adopted to coordinate and integrate flood standards across different regions to avoid adverse "risk transfer" effects. Finally, long-term future climate projection data was comprehensively utilized to scientifically assess changes in extreme rainfall and floods and formulate adaptive policies to address climate change. These recommendations can provide valuable insights for the formulation of flood management and climate change adaptation strategies in China's new era, promoting sustainable development in water resources and hydropower engineering.
Abstract:
The rainfall generation and confluence in small mountainous watersheds exhibit short and rapid runoff response, characterized by abrupt rises and falls during flood events. The short duration and complexity of flood processes pose challenges for flood forecasting in these regions. Moreover, some remote small mountainous watersheds lack well-equipped monitoring stations, resulting in limited hydrological data availability. These areas are considered to appertain lacking or without data regions, where traditional lumped or distributed hydrological models face limitations. Therefore, it is of great significance to conduct the research on the runoff generation and confluence model in small mountainous watersheds. The improved SCS-CN runoff model and the general unit hydrograph confluence method were coupled, and a case at the upper reaches of the Jiuzhou hydrological station in the Xizhijiang River basin, Pearl River basin, was selected for the validation of the proposed model. The three sources Xin'anjiang model was chosen as a reference model for comparison. The flood relative error (Evol), peak relative error (Epeak), peak occurrence time error (Tlag), and Nash-Sutcliffe efficiency coefficient (Dc) as evaluation indicators for model performance. The applicability of the established runoff model in flood simulation in small mountainous watersheds was examined. Results showed that both models demonstrated the applicability in flood simulation in the study basin, with the Xin'anjiang model exhibiting higher accuracy than the SCS-CN general unit hydrograph model. For all 13 flood events, the Xin'anjiang model produced the average Dc was 0.79, with 10 events meeting all accuracy requirements (Evol |≤20%, |Epeak|≤20%, |Tlag|≤3h,and Dc≥0.6), achieving a pass rate of 77%. Regarding the proposed SCS-CN general unit hydrograph model, the average Dc was 0.70, with 9 events meeting all accuracy requirements, achieving a pass rate of 69%. Overall, the accuracy of the Xin'anjiang model was better than the proposed model in the study basin. However, considering of the newly proposed SCS-CN general unit hydrograph model featured a straightforward structure, with parameters that were easy to determine, and was capable of yielding results with acceptable accuracy. It presented a new modeling option for flood forecasting in small mountainous watersheds. Simultaneously, it also provided support for the research of the regionalization law of parameters in general unit hydrograph model.
The rainfall generation and confluence in small mountainous watersheds exhibit short and rapid runoff response, characterized by abrupt rises and falls during flood events. The short duration and complexity of flood processes pose challenges for flood forecasting in these regions. Moreover, some remote small mountainous watersheds lack well-equipped monitoring stations, resulting in limited hydrological data availability. These areas are considered to appertain lacking or without data regions, where traditional lumped or distributed hydrological models face limitations. Therefore, it is of great significance to conduct the research on the runoff generation and confluence model in small mountainous watersheds. The improved SCS-CN runoff model and the general unit hydrograph confluence method were coupled, and a case at the upper reaches of the Jiuzhou hydrological station in the Xizhijiang River basin, Pearl River basin, was selected for the validation of the proposed model. The three sources Xin'anjiang model was chosen as a reference model for comparison. The flood relative error (Evol), peak relative error (Epeak), peak occurrence time error (Tlag), and Nash-Sutcliffe efficiency coefficient (Dc) as evaluation indicators for model performance. The applicability of the established runoff model in flood simulation in small mountainous watersheds was examined. Results showed that both models demonstrated the applicability in flood simulation in the study basin, with the Xin'anjiang model exhibiting higher accuracy than the SCS-CN general unit hydrograph model. For all 13 flood events, the Xin'anjiang model produced the average Dc was 0.79, with 10 events meeting all accuracy requirements (Evol |≤20%, |Epeak|≤20%, |Tlag|≤3h,and Dc≥0.6), achieving a pass rate of 77%. Regarding the proposed SCS-CN general unit hydrograph model, the average Dc was 0.70, with 9 events meeting all accuracy requirements, achieving a pass rate of 69%. Overall, the accuracy of the Xin'anjiang model was better than the proposed model in the study basin. However, considering of the newly proposed SCS-CN general unit hydrograph model featured a straightforward structure, with parameters that were easy to determine, and was capable of yielding results with acceptable accuracy. It presented a new modeling option for flood forecasting in small mountainous watersheds. Simultaneously, it also provided support for the research of the regionalization law of parameters in general unit hydrograph model.
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The Middle Route of South to North Water Diversion Project (MRP) has long canals, involves many areas and hydraulic structures, transfers water by a huge amount, and has various working conditions. These all bring great difficulties to the regulation, control, and management of the project. The technical problem of the engineering lies in the fact that the scientific and mechanism problems behind it are not fully revealed and solved, including multi-dimensional equilibrium control mechanism of multiple water sources under changing conditions, multi-process coupling mechanism of water quantity and water quality, emergency scheduling model for multi-material water pollution, hydraulic response mechanism and control of open channel under multi-gate joint application. In order to establish a complete set of technical system to support its scheduling, this paper summarizes the existing research on the five key points of forecast, scheduling, simulation, control, and evaluation. And on the basis of summarizing the previous research, the key technologies awaiting urgent research are explained in detail, including forecast and scheduling in water source areas and water-receiving areas, multi-phase simulation of water pollution, water quality and water quality control, automatic control technology, evaluation technology, and platform construction. Finally, the paper discusses the scientific problems to be solved in order to realize the intelligent regulation and emergency regulation for the MRP and makes a summary of the research.
The Middle Route of South to North Water Diversion Project (MRP) has long canals, involves many areas and hydraulic structures, transfers water by a huge amount, and has various working conditions. These all bring great difficulties to the regulation, control, and management of the project. The technical problem of the engineering lies in the fact that the scientific and mechanism problems behind it are not fully revealed and solved, including multi-dimensional equilibrium control mechanism of multiple water sources under changing conditions, multi-process coupling mechanism of water quantity and water quality, emergency scheduling model for multi-material water pollution, hydraulic response mechanism and control of open channel under multi-gate joint application. In order to establish a complete set of technical system to support its scheduling, this paper summarizes the existing research on the five key points of forecast, scheduling, simulation, control, and evaluation. And on the basis of summarizing the previous research, the key technologies awaiting urgent research are explained in detail, including forecast and scheduling in water source areas and water-receiving areas, multi-phase simulation of water pollution, water quality and water quality control, automatic control technology, evaluation technology, and platform construction. Finally, the paper discusses the scientific problems to be solved in order to realize the intelligent regulation and emergency regulation for the MRP and makes a summary of the research.
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Based on the T OE theor et ical fr amewo rk ( T echnolo gy2 Or ganizatio n2Environment) and the specific situation of smart water co nstr uction, the TOE framew ork w hich affects smart water constructio n was developed, and the effect s of each impact facto r o n the construction and development o f smar t w ater wer e analyzed from the technical, o rg anizat ional, and env iro nmental dimensions. T he technical dimensio n factors include the technica l superio rity, complex it y, compatibility , and o bser vability. T he org anizational dimension factor s include the const ruction necessity, demand urg ency , and co nstr uction feasibility . The envir on2 mental dimension factor s include the support sy st em, standard system, and info rmation securit y. On the basis, analyt ic hierarchy pr ocess ( AH P) w as used to determine the pr ior ity of the impact facto rs. The results showed that the or ganizatio nal dimensio n facto rs and technical dimension fact ors have hig h impacts on smart water construction w ith the weig ht o f 49% and 31% o ver the index system respect ively. Amo ng the impact factor s, const ruct ion necessity has the hig hest weig ht ( 25%) , follow ed by technical super io rit y ( 16%) , demand urg ency ( 12%) , and construction feasibility ( 12%) . The r esear ch pr ov ides an effectiv ely new metho d fo r the quantitative analy sis of impact factor s of smar t w ater const ruct ion, and the evaluation r esult s can prov ide import ant r eference fo r decision2making of w ater secto r and develo pment of w ater business.
Based on the T OE theor et ical fr amewo rk ( T echnolo gy2 Or ganizatio n2Environment) and the specific situation of smart water co nstr uction, the TOE framew ork w hich affects smart water constructio n was developed, and the effect s of each impact facto r o n the construction and development o f smar t w ater wer e analyzed from the technical, o rg anizat ional, and env iro nmental dimensions. T he technical dimensio n factors include the technica l superio rity, complex it y, compatibility , and o bser vability. T he org anizational dimension factor s include the const ruction necessity, demand urg ency , and co nstr uction feasibility . The envir on2 mental dimension factor s include the support sy st em, standard system, and info rmation securit y. On the basis, analyt ic hierarchy pr ocess ( AH P) w as used to determine the pr ior ity of the impact facto rs. The results showed that the or ganizatio nal dimensio n facto rs and technical dimension fact ors have hig h impacts on smart water construction w ith the weig ht o f 49% and 31% o ver the index system respect ively. Amo ng the impact factor s, const ruct ion necessity has the hig hest weig ht ( 25%) , follow ed by technical super io rit y ( 16%) , demand urg ency ( 12%) , and construction feasibility ( 12%) . The r esear ch pr ov ides an effectiv ely new metho d fo r the quantitative analy sis of impact factor s of smar t w ater const ruct ion, and the evaluation r esult s can prov ide import ant r eference fo r decision2making of w ater secto r and develo pment of w ater business.
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Using precipitation and temperature for the period of 1851-2008 of Xi'an city, the paper analyzed the variation trends and abrupt changes of hydro-meteorological factors including precipitation and temperature using linear fitting, sliding t test, ordered clustering and Mann-Kendall methods．Firstly, the variation trends of precipitation and temperature were analyzed using linear fitting and anomaly percentage, and then the change characteristic of number of rainy days and precipitation were further analyzed. Finally, the paper investigated the abrupt changes of precipitation and temperature using sliding t test, ordered clustering and Mann-Kendall methods. The results showed that the precipitation decreased gradually. Precipitation accounts for 58% of annual precipitation during the flood season and the annual precipitation distribution is uneven. The annual mean temperature and extreme minimum temperature have increased. The abrupt changes of the precipitation were detected in 1958、1975 and 1980, and the abrupt changes of annual average temperature have found between 1993-1995.
Using precipitation and temperature for the period of 1851-2008 of Xi'an city, the paper analyzed the variation trends and abrupt changes of hydro-meteorological factors including precipitation and temperature using linear fitting, sliding t test, ordered clustering and Mann-Kendall methods．Firstly, the variation trends of precipitation and temperature were analyzed using linear fitting and anomaly percentage, and then the change characteristic of number of rainy days and precipitation were further analyzed. Finally, the paper investigated the abrupt changes of precipitation and temperature using sliding t test, ordered clustering and Mann-Kendall methods. The results showed that the precipitation decreased gradually. Precipitation accounts for 58% of annual precipitation during the flood season and the annual precipitation distribution is uneven. The annual mean temperature and extreme minimum temperature have increased. The abrupt changes of the precipitation were detected in 1958、1975 and 1980, and the abrupt changes of annual average temperature have found between 1993-1995.
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Sensitivity analysis was performed to analyze the inputs and outputs of the complex model and system qualitatively and quantitatively, which can benefit the inspection of model structure, identification of model parameters, and model application. In this paper, Sobol method was applied to evaluate the sensitivity of single parameter and multiple parameters of the model in the Huanren reservoir catchment. The objective functions of sensitivity analysis included the deterministic coefficients and error coefficients of total water, low flow, and high flow. The results showed that the sensitivity of parameters was different under different objective functions, and Sobol method can provide the sensitivity for all parameters and sensitivity between each parameter, which is useful for sensitivity analysis of hydrological models.
Sensitivity analysis was performed to analyze the inputs and outputs of the complex model and system qualitatively and quantitatively, which can benefit the inspection of model structure, identification of model parameters, and model application. In this paper, Sobol method was applied to evaluate the sensitivity of single parameter and multiple parameters of the model in the Huanren reservoir catchment. The objective functions of sensitivity analysis included the deterministic coefficients and error coefficients of total water, low flow, and high flow. The results showed that the sensitivity of parameters was different under different objective functions, and Sobol method can provide the sensitivity for all parameters and sensitivity between each parameter, which is useful for sensitivity analysis of hydrological models.
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Accurate and rapid determination of the distribution of contaminants is the main task for the investigation work of a contaminated site. As a new surveying tool for contaminated sites, direct push technology can be used for soil sample collection in the vadoze zone and aquifer, detection of aquifer parameters, and determination of pollutants. It has the advantages of fast, accurate, and free of cross-contamination. In this paper, the development and research progress of direct push technology was introduced, and the technology innovation was discussed.
Accurate and rapid determination of the distribution of contaminants is the main task for the investigation work of a contaminated site. As a new surveying tool for contaminated sites, direct push technology can be used for soil sample collection in the vadoze zone and aquifer, detection of aquifer parameters, and determination of pollutants. It has the advantages of fast, accurate, and free of cross-contamination. In this paper, the development and research progress of direct push technology was introduced, and the technology innovation was discussed.
Abstract:
"National River Linking Project (NRLP)" is a large-scale hydraulic engineering project that aims to reduce the persistent water shortage problems in India. In, this paper, describes the target planning and progress of the NRLPNational River Linking Project, was described, and introduces the program’s management system of this project and water policy in India was introduced. Due to the large scale of the project, it involves involved the deployment and utilization of water resources and utilization inof the many rivers of the South Peninsula, therefore several problems exist in the implementation of the project such as the funding stress, international development of transboundary rivers, and ecological environment. this paper addresses and analyzes the basic problems based on the project’s main benefit goals.
"National River Linking Project (NRLP)" is a large-scale hydraulic engineering project that aims to reduce the persistent water shortage problems in India. In, this paper, describes the target planning and progress of the NRLPNational River Linking Project, was described, and introduces the program’s management system of this project and water policy in India was introduced. Due to the large scale of the project, it involves involved the deployment and utilization of water resources and utilization inof the many rivers of the South Peninsula, therefore several problems exist in the implementation of the project such as the funding stress, international development of transboundary rivers, and ecological environment. this paper addresses and analyzes the basic problems based on the project’s main benefit goals.
Abstract:
Environmental Kuznets Curve (EKC) hypothesis has instructive significance to explore the relationship between environmental protection and economic development and to seek the coordinated development of economy and environment. Based on the analysis of the basic conception of EKC hypothesis, the research progress of the impact factors, theoretical developments, and empirical studies of EKC were illustrated in this paper, and the existing problems of the hypothesis were also discussed. Finally, it was noted that under the international trade conditions, the developing countries should study the clean technology, policy reformation, public education, and environmental law system from the developed countries, which can help them decrease the EKC turn point, flatten EKC curve, and seek for win-win relationship between economy and environment.
Environmental Kuznets Curve (EKC) hypothesis has instructive significance to explore the relationship between environmental protection and economic development and to seek the coordinated development of economy and environment. Based on the analysis of the basic conception of EKC hypothesis, the research progress of the impact factors, theoretical developments, and empirical studies of EKC were illustrated in this paper, and the existing problems of the hypothesis were also discussed. Finally, it was noted that under the international trade conditions, the developing countries should study the clean technology, policy reformation, public education, and environmental law system from the developed countries, which can help them decrease the EKC turn point, flatten EKC curve, and seek for win-win relationship between economy and environment.
Abstract:
The analysis of the night minimum flow data in the Districted Metered Area (DMA) of the water distribution system can characterize the real loss of DMA. The high-frequency and high-accuracy measured night flow data were analyzed, which indicated that the night flow data of DMA at different time periods are in normal distribution and the lowest night flow data is close to the real loss of DMA. In this study, the minimum night flow data from 2 AM to 4 AM in the early morning were analyzed based on the confidence level of 95.5% and confidence interval of (m-2d, m+2d).. The results showed that the minimum night flow of DMA after removing the abnormal values characterized by m-2dcan eliminate the effects of error and interference of measured data, and therefore obtain the real loss of DMA. This method can lower the evaluation error of night water demand, and facilitate the in-situ meter flow measurement to assess the DMA leakage level quickly.
The analysis of the night minimum flow data in the Districted Metered Area (DMA) of the water distribution system can characterize the real loss of DMA. The high-frequency and high-accuracy measured night flow data were analyzed, which indicated that the night flow data of DMA at different time periods are in normal distribution and the lowest night flow data is close to the real loss of DMA. In this study, the minimum night flow data from 2 AM to 4 AM in the early morning were analyzed based on the confidence level of 95.5% and confidence interval of (m-2d, m+2d).. The results showed that the minimum night flow of DMA after removing the abnormal values characterized by m-2dcan eliminate the effects of error and interference of measured data, and therefore obtain the real loss of DMA. This method can lower the evaluation error of night water demand, and facilitate the in-situ meter flow measurement to assess the DMA leakage level quickly.
Abstract:
Based on the daily data of precipitation and temperature of 30 basic meteorological stations during the period 1956-2010, twelve indices characterizing extreme climate change have been selected to analyze the temporal changes in precipitation and temperature extremes in the Hai River Basin. As per many other parts of the world, the analysis shows an increase in the intensity, frequency and duration of high temperature extremes and a decrease in that of cold extremes. The intensity of short-time precipitation extremes shows an increase and the frequency of heavy precipitation shows a decrease. The consecutive wet days shows a decrease, while the consecutive dry days shows an increase in recent decades, thus the dry pattern has been aggravated in the basin. The annual high temperature extremes and short-time precipitation extremes have begun to frequently occur since 1990s from interdecadal variations, the rainfall of long-duration precipitation events has shown a decrease however. The general warm and dry trend and precipitation concentration will have a negative impact on the agriculture production and water resources development. Meanwhile, the increase of short-time precipitation extremes may exacerbate the risk of local flood disaster in mountainous area as well as urban waterlogging.
Based on the daily data of precipitation and temperature of 30 basic meteorological stations during the period 1956-2010, twelve indices characterizing extreme climate change have been selected to analyze the temporal changes in precipitation and temperature extremes in the Hai River Basin. As per many other parts of the world, the analysis shows an increase in the intensity, frequency and duration of high temperature extremes and a decrease in that of cold extremes. The intensity of short-time precipitation extremes shows an increase and the frequency of heavy precipitation shows a decrease. The consecutive wet days shows a decrease, while the consecutive dry days shows an increase in recent decades, thus the dry pattern has been aggravated in the basin. The annual high temperature extremes and short-time precipitation extremes have begun to frequently occur since 1990s from interdecadal variations, the rainfall of long-duration precipitation events has shown a decrease however. The general warm and dry trend and precipitation concentration will have a negative impact on the agriculture production and water resources development. Meanwhile, the increase of short-time precipitation extremes may exacerbate the risk of local flood disaster in mountainous area as well as urban waterlogging.
Abstract:
Compared with the traditional determined hydrologic forecast, hydrologic ensemble forecast contains various uncertainties in the hydrologic forecast processes. Therefore, the accuracy and validity of hydrologic forecast have been improved theoretically. Meanwhile, the cognitive and predictive capabilities of the events such as storm, flood, and drought have been enhanced in the practical applications. The hydrologic ensemble forecast can provide more accurate and useful information in flood control, drought relief, and sustainable water resources management. In this paper, we firstly reviewed the history of hydrologic ensemble forecast, and then we summarized the research progresses in theory, methods, as well as the applications and operational hydrologic ensemble forecast. We focused on two research aspects of the pre-processing and post-processing issues in an effort to provide a useful platform for the development of hydrologic ensemble prediction. The perspectives and recommendations on this subject were provided. This paper is of important significance in the future development of hydrologic ensemble forecast research.
Compared with the traditional determined hydrologic forecast, hydrologic ensemble forecast contains various uncertainties in the hydrologic forecast processes. Therefore, the accuracy and validity of hydrologic forecast have been improved theoretically. Meanwhile, the cognitive and predictive capabilities of the events such as storm, flood, and drought have been enhanced in the practical applications. The hydrologic ensemble forecast can provide more accurate and useful information in flood control, drought relief, and sustainable water resources management. In this paper, we firstly reviewed the history of hydrologic ensemble forecast, and then we summarized the research progresses in theory, methods, as well as the applications and operational hydrologic ensemble forecast. We focused on two research aspects of the pre-processing and post-processing issues in an effort to provide a useful platform for the development of hydrologic ensemble prediction. The perspectives and recommendations on this subject were provided. This paper is of important significance in the future development of hydrologic ensemble forecast research.
Abstract:
As a quantitative indicator of drought, drought index plays an important role in the monitoring and forecasting of drought and water resources management, and it is also a useful research tool in the field of hydrology and water resources. Over the last decade, the primary progress in the development and improvement of drought index involved the introduction of evapotranspiration as a factor of the index calculation, which can improve the parameter accuracy in model simulation and combine with the model algorithm of hydrological process. The application of drought index included the inversion and prediction of regional drought, crop yield prediction, forest fire detection, and paleoclimate reconstruction. The development and application of drought index provided an effective tool for regional drought monitoring and water resources management; however, the quantification and comprehensive evaluation of drought index should be considered as research priorities, which can help improve the accuracy and reliability of model monitoring and thus provide new options and technical approaches for rapid monitoring of drought.
As a quantitative indicator of drought, drought index plays an important role in the monitoring and forecasting of drought and water resources management, and it is also a useful research tool in the field of hydrology and water resources. Over the last decade, the primary progress in the development and improvement of drought index involved the introduction of evapotranspiration as a factor of the index calculation, which can improve the parameter accuracy in model simulation and combine with the model algorithm of hydrological process. The application of drought index included the inversion and prediction of regional drought, crop yield prediction, forest fire detection, and paleoclimate reconstruction. The development and application of drought index provided an effective tool for regional drought monitoring and water resources management; however, the quantification and comprehensive evaluation of drought index should be considered as research priorities, which can help improve the accuracy and reliability of model monitoring and thus provide new options and technical approaches for rapid monitoring of drought.
Abstract:
With the r apid development o f meso scale numer ical at mospher ic model WRF in r ecent y ears, its application is wider and w ider. In or der to ex plain the mechanism, r eveal the develo pment directio n and pr ov ide refer ence for r elated fields research2 er s, WRF model sy stem is int roduced, it is discussed that the influence o f parameterized phy sical pr ocesses, data assimilatio n and reasonable spat ial scale o n the simulation effect o f WRF model. Related studies have shown that: ( 1) differ ent par ameter2 ized phy sical processes need to be chosen in different reg ion and different time; ( 2) the common data assimilation method is 3DVar data assimilatio n at present, hybr id data assimilatio n may be a better met ho d to impr ove the simulatio n effect of WRF model; ( 3) reasonable spat ial scales need to be cho sen because not the hig her hor izo nt al reso lution, t he better simulat ion effect for a ll research; ( 4) WRF mo del has g oo d simulat ion effect , hig h pr ediction accuracy , there is mo re w ide applicat ion.
With the r apid development o f meso scale numer ical at mospher ic model WRF in r ecent y ears, its application is wider and w ider. In or der to ex plain the mechanism, r eveal the develo pment directio n and pr ov ide refer ence for r elated fields research2 er s, WRF model sy stem is int roduced, it is discussed that the influence o f parameterized phy sical pr ocesses, data assimilatio n and reasonable spat ial scale o n the simulation effect o f WRF model. Related studies have shown that: ( 1) differ ent par ameter2 ized phy sical processes need to be chosen in different reg ion and different time; ( 2) the common data assimilation method is 3DVar data assimilatio n at present, hybr id data assimilatio n may be a better met ho d to impr ove the simulatio n effect of WRF model; ( 3) reasonable spat ial scales need to be cho sen because not the hig her hor izo nt al reso lution, t he better simulat ion effect for a ll research; ( 4) WRF mo del has g oo d simulat ion effect , hig h pr ediction accuracy , there is mo re w ide applicat ion.
Abstract:
The instantaneous peak flow (IPF) is the basic information for hydraulic design，construction and management. It also has an important influence on the investment and safety of hydraulic structures. However, the IPF records in Tibet are generally short in length, while mean daily flow (MDF) records are relatively longer. In this study, the IPF records are extended by analyzing the relationship between corresponding IPF and MDF records. The results show that the ratio between IPF and MDF is stable in most of hydrological stations. The relative error between estimated IPF and observed IPF is less than 10%. The results of flood frequency analysis using extended IPF series are more reasonable than that using the measured IPF series. For the stations with limited measured MDF, the HIMS model is used to extend the available MDF. The HIMS model is applied in three representative rivers of Tibet: the Nianchu river, Lhasa river and Niang river. The results show that the model has a good performance in both daily and peak flow simulation. The end year of IPF series in the three representative hydrological stations has been extended from 2000 to 2010 by the simulation results of HIMS and the relationship between IPF and MDF.
The instantaneous peak flow (IPF) is the basic information for hydraulic design，construction and management. It also has an important influence on the investment and safety of hydraulic structures. However, the IPF records in Tibet are generally short in length, while mean daily flow (MDF) records are relatively longer. In this study, the IPF records are extended by analyzing the relationship between corresponding IPF and MDF records. The results show that the ratio between IPF and MDF is stable in most of hydrological stations. The relative error between estimated IPF and observed IPF is less than 10%. The results of flood frequency analysis using extended IPF series are more reasonable than that using the measured IPF series. For the stations with limited measured MDF, the HIMS model is used to extend the available MDF. The HIMS model is applied in three representative rivers of Tibet: the Nianchu river, Lhasa river and Niang river. The results show that the model has a good performance in both daily and peak flow simulation. The end year of IPF series in the three representative hydrological stations has been extended from 2000 to 2010 by the simulation results of HIMS and the relationship between IPF and MDF.
Abstract:
The objective of this study is to evaluate the applicability of SWAT model to agricultural drought evaluation for regions without or lack of soil moisture data. For this purpose, the SWAT model was applied to simulate the hydrological process in the Bahe watershed of the upper Weihe River. The soil water content was obtained and it was used to calculate the relative soil moisture. The calculated relative soil moisture was regarded as the evaluation index of agricultural drought. The results showed that severe spring droughts occurred in 2001 and 2002 and summer drought occurred in 2003 in the Bahe watershed, which was in accordance with the actual conditions. . Therefore, SWAT model is applicable to agricultural drought evaluation for the area lack of soil moisture data.
The objective of this study is to evaluate the applicability of SWAT model to agricultural drought evaluation for regions without or lack of soil moisture data. For this purpose, the SWAT model was applied to simulate the hydrological process in the Bahe watershed of the upper Weihe River. The soil water content was obtained and it was used to calculate the relative soil moisture. The calculated relative soil moisture was regarded as the evaluation index of agricultural drought. The results showed that severe spring droughts occurred in 2001 and 2002 and summer drought occurred in 2003 in the Bahe watershed, which was in accordance with the actual conditions. . Therefore, SWAT model is applicable to agricultural drought evaluation for the area lack of soil moisture data.
Abstract:
Static cone penetration test (CPT) as is an in situ test, which is was widely used in the engineering practice. Based on recently research results, thise paper systematically introduced sums up the research and development course in of CPT and summarized the research progress of the, such as instrument development, cone resistance theoretical research of cone resistance, model test, numerical simulation, and engineering application of CPT. Empirical formula of to calculate the soil parameters using CPT on for different industries and different areas were summarized. The paper pointed out that iIt is necessary to fully consider the engineering characteristics of regional soil when using in application of the CPT results. Moreover, It should be point out that the theoretical analysis of excess pore water pressure, analytic solution of cylindrical hole space problem, and numerical analysis simulation for large deformation analysis theory need to be further improved..
Static cone penetration test (CPT) as is an in situ test, which is was widely used in the engineering practice. Based on recently research results, thise paper systematically introduced sums up the research and development course in of CPT and summarized the research progress of the, such as instrument development, cone resistance theoretical research of cone resistance, model test, numerical simulation, and engineering application of CPT. Empirical formula of to calculate the soil parameters using CPT on for different industries and different areas were summarized. The paper pointed out that iIt is necessary to fully consider the engineering characteristics of regional soil when using in application of the CPT results. Moreover, It should be point out that the theoretical analysis of excess pore water pressure, analytic solution of cylindrical hole space problem, and numerical analysis simulation for large deformation analysis theory need to be further improved..
Abstract:
Wetlands and aAtmosphere constantly engaged in the exchange of energy and material constantly, that is , free water surface of wetland and dense vegetation was are in the process of evapotranspirationthrough evapo-transpiration to enter into the atmosphere and a part of water returns to the groundwater as precipitation, thereby increasing the so that water vapour injected into the atmosphere， then formed the rain and returned to the ground, thereby it improved local humidity and precipitation. In this paper, Based on the precipitation data from 1974～2010 of Hengshui Lake and twenty- four24 nearby rRainfall sStations from 1974 to 2010 were used to calculate of periphery ， this article figured out the average precipitation of the Hengshui Lake District ，10- km radius affected zone, 10～2010- to 20- km circular affected zone， and 20- to～30- km circular affected zone. It analyzed theThe effects of the wetland of Hengshui Lake on precipitation were analyzed, and the main reasons were investigated based on the change regularity of different affected zone of Hengshui Lake wetland, and explore the main reason through precipitation formation mechanism of precipitation. The result showsed: that the precipitation decreases Hengshui Lake wetland from the near to the distant distance of the Hengshui Lake Wetland, indicating was obviously decreasing, it revealed that Hengshui Lake wetland has an adjustment function the adjustment effects of the wetland onto the climate of surrounding regional climatearea.
Wetlands and aAtmosphere constantly engaged in the exchange of energy and material constantly, that is , free water surface of wetland and dense vegetation was are in the process of evapotranspirationthrough evapo-transpiration to enter into the atmosphere and a part of water returns to the groundwater as precipitation, thereby increasing the so that water vapour injected into the atmosphere， then formed the rain and returned to the ground, thereby it improved local humidity and precipitation. In this paper, Based on the precipitation data from 1974～2010 of Hengshui Lake and twenty- four24 nearby rRainfall sStations from 1974 to 2010 were used to calculate of periphery ， this article figured out the average precipitation of the Hengshui Lake District ，10- km radius affected zone, 10～2010- to 20- km circular affected zone， and 20- to～30- km circular affected zone. It analyzed theThe effects of the wetland of Hengshui Lake on precipitation were analyzed, and the main reasons were investigated based on the change regularity of different affected zone of Hengshui Lake wetland, and explore the main reason through precipitation formation mechanism of precipitation. The result showsed: that the precipitation decreases Hengshui Lake wetland from the near to the distant distance of the Hengshui Lake Wetland, indicating was obviously decreasing, it revealed that Hengshui Lake wetland has an adjustment function the adjustment effects of the wetland onto the climate of surrounding regional climatearea.
Abstract:
A proposed water transfer tunnel will be excavated with tunnel boring machine (TBM) in the surrounding type-III rock. The shotcrete and reinforced concrete segment serve as the initial support and permanent liner, respectively. The considerable internal and external water pressures are loaded on the liner, with the water head values of 110 m and 200 m, respectively. In this paper, in consideration of the contact relationship between segments, the contact relationship between segment and surrounding structure, and the cooperative working performance of reinforcement bars and concrete, the stress deformation characteristics of the liner under high water pressures are analyzed using the finite element method. The results showed that the external water pressure is the decisive load for the design of tunnel liner, and therefore a simplified model of segment liner design was proposed. The results suggested that it is feasible to use the reinforced concrete segment as tunnel lining under the conditions of the surrounding rock, support, and water pressure shown in the study.
A proposed water transfer tunnel will be excavated with tunnel boring machine (TBM) in the surrounding type-III rock. The shotcrete and reinforced concrete segment serve as the initial support and permanent liner, respectively. The considerable internal and external water pressures are loaded on the liner, with the water head values of 110 m and 200 m, respectively. In this paper, in consideration of the contact relationship between segments, the contact relationship between segment and surrounding structure, and the cooperative working performance of reinforcement bars and concrete, the stress deformation characteristics of the liner under high water pressures are analyzed using the finite element method. The results showed that the external water pressure is the decisive load for the design of tunnel liner, and therefore a simplified model of segment liner design was proposed. The results suggested that it is feasible to use the reinforced concrete segment as tunnel lining under the conditions of the surrounding rock, support, and water pressure shown in the study.
Abstract:
Based on the monthly precipitation data of 25 meteorological stations in the Haihe River Basin from 1960 to 2010, the inter 2annual precipitation characteristics in the Haihe River Basin were analyzed using the linear regression and cumulative a 2 nomaly curve methods. T he probability distribution of precipitation was analyzed using the Pearson III curve method, and the spatial variation of precipitation was analyzed using the spatial interpolation method. T he results showed that (1) precipitation in the Haihe River Basin has a slightly decreasing trend in recent 51 years, and the decreasing trend is stable recently; ( 2) there is a trend with more wet years while less dry years in the Haihe River Basin and the trend is increasing; (3) seasonal variation of precipitation is obvious; and (4) precipitation decreases trend from the south to the north.
Based on the monthly precipitation data of 25 meteorological stations in the Haihe River Basin from 1960 to 2010, the inter 2annual precipitation characteristics in the Haihe River Basin were analyzed using the linear regression and cumulative a 2 nomaly curve methods. T he probability distribution of precipitation was analyzed using the Pearson III curve method, and the spatial variation of precipitation was analyzed using the spatial interpolation method. T he results showed that (1) precipitation in the Haihe River Basin has a slightly decreasing trend in recent 51 years, and the decreasing trend is stable recently; ( 2) there is a trend with more wet years while less dry years in the Haihe River Basin and the trend is increasing; (3) seasonal variation of precipitation is obvious; and (4) precipitation decreases trend from the south to the north.
Abstract:
The impacts of human activities and dry climate aggravate the water pollution and eutrophication in the Baiyang Lake. Through the analysis of hydro 2chemical compositions of the water, five indexes[Chla, TN, T P, COD Mn, and SD] , which are re 2 lated to water eutrophication, are selected as evaluation parameters, and the comprehensive nutrition index method is adopted to determine the water eutrophication type. T he results of water quality monitoring data show that the type of water is CNaII, and the lake is in mesotrophic or eutrophic state determined by the comprehensive nutrition index method. The principal component analysis results show that TP is the main factor to cause water pollution in the lake. According to the analysis of diatom and its combination, the diatom in the lake is characterized by the combination of eutrophic species Cyclotellameneghiniana ( 20. 43%) and Cyclostep hanos tholif ormis ( 25. 40%) , which indicates that the lake is in the eutrophication state and water environment is in danger.
The impacts of human activities and dry climate aggravate the water pollution and eutrophication in the Baiyang Lake. Through the analysis of hydro 2chemical compositions of the water, five indexes[Chla, TN, T P, COD Mn, and SD] , which are re 2 lated to water eutrophication, are selected as evaluation parameters, and the comprehensive nutrition index method is adopted to determine the water eutrophication type. T he results of water quality monitoring data show that the type of water is CNaII, and the lake is in mesotrophic or eutrophic state determined by the comprehensive nutrition index method. The principal component analysis results show that TP is the main factor to cause water pollution in the lake. According to the analysis of diatom and its combination, the diatom in the lake is characterized by the combination of eutrophic species Cyclotellameneghiniana ( 20. 43%) and Cyclostep hanos tholif ormis ( 25. 40%) , which indicates that the lake is in the eutrophication state and water environment is in danger.
Abstract:
Thro ug h the analysis of t he technique, envir onment, law , and eco nomy in the manag ement and operatio n o f inter2basin water transfer projects abro ad, this paper summar ized the successful ex per ience o f int er2basin w ater tr ansfer pr ojects in the wo rld fr om the aspects of leg islat ion, w ater r ig ht s, water pr ice, unified manag ement o f water resources, investment manag ement of eng ineering const ruct ion, and management o per ation mode, w hich can pro vide t he refer ence fo r the o per ation of inter2basin water transfer pro jects in China.
Thro ug h the analysis of t he technique, envir onment, law , and eco nomy in the manag ement and operatio n o f inter2basin water transfer projects abro ad, this paper summar ized the successful ex per ience o f int er2basin w ater tr ansfer pr ojects in the wo rld fr om the aspects of leg islat ion, w ater r ig ht s, water pr ice, unified manag ement o f water resources, investment manag ement of eng ineering const ruct ion, and management o per ation mode, w hich can pro vide t he refer ence fo r the o per ation of inter2basin water transfer pro jects in China.
Periodical information
Competent Authority:Department of Water Resources of Hebei Procince
Sponsored by:Hebei Institute of Water Resources
Chief Editor :ZHANG Shuantang
Edited and Published by:The Editorial Dept South-to-North Water Transfers and Water Science &Technology
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