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[摘要]
为了“诊断”华北平原典型灌区农田水循环的“病症”和“病状”,在解析灌区农田水循环结构的基础上,提出农田健康水循环的概念,选用层次分析熵权组合法计算权重,构建灌区尺度农田水循环健康评价体系;分别采用综合指数法和改进的灰色关联分析对比评价军留灌区2010—2019年农田水循环健康状况。指标评价结果显示:军留灌区在灌溉水质、化肥及农药非点源污染、灌溉水利用系数等方面多呈现“病态”,结果为“一般”及以上的指标总个数由2010年的4个增长至2019年的9个;维度评价结果显示,退排水子过程的健康状况最差,基本处于“病态”,水源、取输水子过程、用耗水子过程的水循环健康状况得到逐年提升。总体而言,军留灌区水循环状态近10年得到了逐年改善,并且2种方法的维度或综合评价结果的变化趋势基本一致。研究结果可为华北平原灌区精细化管理和绿色高质量发展提供科学依据和决策参考。
[Key word]
[Abstract]
With the rapid increase of population,agricultural water demand has increased largely,which resulted in the continuous construction of irrigation and water conservancy projects.The effect of artificial drive force on farmland water cycle has become more and more prominent,especially in the main grain-producing areas such as the North China Plain,which led to the "nature-society" duality of the farmland water cycle in the irrigated areas.In past years,the irrigation managers only focused on human living and economic benefits,while ignored the natural law and farmland sustainability,caused groundwater over-pumping and ecological environment deterioration,then influenced the high-quality agricultural production in the irrigated area.Thus,to solve the above problems,it is crucial to systematically illustrate the farmland water-cycle "health" and scientifically "diagnose" the related "symptoms". Based on the analysis on the structure and the corresponding health conception of farmland watercycle in irrigation areas,the evaluation index system of farmland watercycle health including four dimensions (water source,water transporting,water consumption,and water withdrawal & drainage) and fifteen indexes were established,according to the selection principle of Analytic Hierarchy Process.The indexes' weight through the combined Analytic Hierarchy Process-Entropy Weight Method were calculated to improve the corresponding objectivity.The threshold values of different health grades in the evaluation index system of farmland water-cycle were set according to the relevant national standards and reference to the related researches.Junliu irrigated area of Wei county,Hebei province was selected as the typical one of the North China Plain.The health of regional farmland water-cycle from 2010 to 2019 was evaluated through comprehensive index method and modified grey correlation analysis,respectively. The index evaluation results show that:the water quality,non-point water pollution of fertilizer and pesticide,and utilization coefficient of irrigation water are mostly "ill";the indexes such as water source diversity,the leakage proportion of canal irrigation water,the piping proportion of field irrigation water,the high-efficiency proportion of water-saving irrigation and reasonableness of planting structure have improved year by year in recent years.The total number of "normal" and healthier grades increased from four in 2010 to nine in 2019.The dimension evaluation results show that the health of water withdrawal and drainage is the worst and most of all are in "sick";while the health of the water source,water transport,and water consumption was improved year by year.The two comprehensive evaluation results both show that the water cycle in the Junliu irrigation area has been improved gradually in the recent decade.The evaluation results of grey correlation analysis show that the health grades of farmland watercycle are "seriously ill" from 2010 to 2015,then upgraded to "normal" in 2016,and reached a stable grade in 2017 and later maintain "sub-health".The scores of the comprehensive index method range from 2.36 to 3.58,and the corresponding health grade was gradually improved from "sick" in 2010 to "normal" after 2015. It is indicated that the comprehensive health of farmland water-cycle in Junliu irrigation area has gradually improved in the recent ten years due to the integrated management of groundwater over-pumping.The non-point water pollution of fertilizer and pesticide is the critical focus for the irrigation.The comprehensiveness and dimension health trends of grey correlation analysis and comprehensive index method are similar.By contrast,the results of grey correlation analysis are more reasonable as the healthy scores approach the critical value,while the results of the comprehensive index method are relatively objective to the whole trend indication.The results could provide a scientific basis and decision-making reference to the management and high-quality development of irrigated areas in the North China Plain.
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