干旱遭遇会严重影响跨流域调水工程的效益发挥，为科学评估引江济淮工程水源区和受水区的干旱遭遇风 险，采用标准化降水蒸散指数（standardized?precipitation?evapotranspiration?index，SPEI）和 Copula 理论构建水源区和 受水区干旱指数的联合分布，分析历史和未来两个区域干旱演变规律以及干旱遭遇风险变化。结果表明： 1960—2020 年水源区和受水区发生干旱的频率分别为 27.32% 和 29.78%；未来情景下两个区域干旱发生频率均 有明显增加，尤其高排放情景下特旱发生频率增加超过 10%；非汛期水源区和受水区同时发生干旱的概率比汛期 高 5.49%；未来汛期和全年干旱遭遇频率预计有明显增加，非汛期干旱遭遇频率略有降低；在中高排放情景下 （SSP2-4.5 和 SSP5-8.5），远期干旱遭遇频率相对更高。干旱遭遇风险增加对跨流域调水工程效益发挥带来了巨大 挑战，因此迫切需要制定适应性策略，为调水工程正常运行管理和水资源可持续利用提供保障。

The?inter-basin?water?diversion?projects?transfer?the?water?resources?from?basins?with?abundant?water?to that?with?scarce?water,?which?aims?to?address?the?problem?of?uneven?spatial?and?temporal?distribution?of?water resources.?The?Yangtze-to-Huaihe?River?Water?Diversion?Project?is?a?major?strategic?water?resource?allocation project?across?Yangtze?River?and?Huaihe?River?basins.?The?middle?and?lower?reaches?of?the?Yangtze?River?and?the Huaihe?River?basin?are?located?in?the?eastern?monsoon?region?of?China.?The?drought?disasters?occur?frequently?in these?regions?with?the?influence?of?monsoon?climate.?Due?to?the?temporal?fluctuation?and?spatial?variability?of regional?water?supply,?the?water?source?and?the?water?destination?regions?of?the?project?are?prone?to?the?risk?of concurrent ?droughts. ?The ?simultaneous ?occurrence ?of ?drought ?events ?across ?the ?water ?source ?and ?the ?water destination?regions?or?other?conditions?that?are?not?conducive?to?water?transfer?would?have?a?significant?impact?on the?normal?scheduling?operation?and?efficiency?of?the?project.?In?addition,?with?the?effects?of?climate?change?and human?activities,?the?global?water?cycle?will?be?further?intensified.?Compound?extreme?events?such?as?drought,?high temperature?and?heat?waves?on?a?global?scale?will?be?increasing,?which?have?a?serious?impact?on?regional?water resources ?management, ?ecosystem ?and ?sustainable ?socio-economic ?development. ?Therefore, ?it ?is ?of ?great significance?to?explore?the?risk?of?concurrent?drought?in?the?water?source?and?the?water?destination?regions?of?the Yangtze-to-Huaihe ?River ?Water ?Diversion ?Project ?under ?climate ?change ?to ?provide ?scientific ?support ?for ?the operation?of?project?scheduling?and?sustainable?utilization?of?water?resources. ??????The?risk?of?concurrent?drought?probability?between?the?water?source?and?destination?regions?of?Yangtze-to- Huaihe?River?Water?Diversion?Project?was?investigated.?The?meteorological?observation?and?the?Coupled?Model Intercomparison?Project?Phase?6?(CMIP6)?climate?model?dataset?of?precipitation?were?integrated?for?both?historical and?future?assessment.?Precipitation?from?nine?CMIP6?dataset?with?three?scenarios?was?first?bias-corrected?using?a quantile?mapping?approach.?The?Standardized?Precipitation?Evapotranspiration?Index?(SPEI)?with?a?time?scale?of?6 and ?12 ?months ?was ?calculated ?by ?monthly ?precipitation ?and ?temperature ?to ?describe ?drought ?condition. ?The appropriate?marginal?distribution?was?selected?to?fit?the?SPEI?sequence.?The?Copula?theory?was?then?applied?to construct?the?joint?distribution?of?drought?index?in?the?water?source?and?destination?regions.?The?drought?evolution patterns?and?drought?encounter?risks?from?1960?to?2020?were?evaluated.?And?further?analysis?of?the?future?changes in?drought?encounter?risks?under?different?scenarios?based?on?CMIP6?data?was?carried?out. ??????The?results?showed?that?the?frequency?of?drought?occurrence?in?the?water?source?and?destination?regions?from 1960?to?2020?was?27.32%?and?29.78%?respectively.?In?the?future?scenarios,?there?would?be?a?significant?increase?in the?frequency?of?drought?occurrence?in?both?regions,?especially?in?the?high?emission?scenario?where?the?frequency?of severe?drought?occurrence?increases?by?more?than?10%.?The?probability?of?simultaneous?drought?occurrence?in?the non-flood?season?of?the?water?source?and?destination?regions?was?5.49%?higher?compared?to?the?flood?season.?The frequency?of?drought?encounters?during?the?flood?season?and?throughout?the?year?was?expected?to?significantly increase,?while?the?frequency?of?non-flood?season?drought?encounters?was?slightly?reduced.?In?the?medium?to?high emission?scenarios?(SSP2-4.5?and?SSP5-8.5),?the?frequency?of?long-term?drought?encounters?was?relatively?higher. ??????The?SPEI?could?well?capture?the?regional?drought?conditions?in?both?the?water?source?and?destination?regions. The?joint?distribution?of?SPEI?by?the?Clayton?Copula?function?was?capable?to?characterize?the?concurrent?drought between?the?water?source?and?destination?regions.?The?probability?of?concurrent?drought?in?the?two?regions?during the?non-flood?season?was?relatively?higher?than?that?in?the?flood?season.?In?the?future?scenarios,?there?would?be?a significant?increase?in?the?frequency?of?drought?occurrence?in?both?regions.?And?the?frequency?of?drought?encounters was?also?projected?to?increase?in?the?future.?Therefore,?it?is?urgent?to?formulate?adaptive?strategies?to?ensure?the normal?operation?management?of?water?transfer?projects?and?the?sustainable?utilization?of?water?resources.