基于多方法综合比较的南水北调西线工程水源区生态需水研究

Research on ecological water demand in water source area of west route of South-to-North Water Diversion Project based on multi-method comprehensive comparison

针对南水北调西线工程调水需求,以方法比选、目标修正、可行性验证为主线,提出了一套多方法综合确定水源区生态需水过程的思路,并制定了10个坝址断面枯水期和非枯水期的生态基流、敏感生态需水及年生态水量目标。结果表明:水源区坝址断面枯水期生态基流在多年平均流量中的占比约为20%,非枯水期占比约为40%;3—6月为鱼类集中产卵敏感期,需要每月发生一次脉冲流量过程,每次至少持续10 d,脉冲流量在多年平均流量中的占比为48%~73%;各坝址断面年均生态水量在多年平均径流量中的占比约为70%,其中丰水年、一般偏枯年、枯水年生态水量占比分别为68%~78%、66%~75%和61%~70%;研究结果符合长江流域现有管控要求,具备较好的现实可达性。

According to practical requirements of water transfer in west route of the South-to-North Water Diversion Project,an idea of multi-method comprehensive determination of ecological water demand process in water source area was proposed based on method comparison,target adjustment,feasibility verification,and the ecological base flow in dry and non-dry periods,sensitive ecological water demand,and annual ecological water volume targets at 10 dam site sections were formulated.The results indicate that the ecological base flow at dam site sections in the water source area accounts for approximately 20%of the multi-year average flow in dry period,increasing to about 40%in non-dry period.The period from March to June is critical for fish spawning,necessitating monthly pulse flow events lasting at least 10 days each,and the pulse flow accounts for 48%to 73%of the total multi-year average flow.The proportion of the average annual ecological water volume at dam site sections to the multi-year average runoff is approximately 70%,and the proportion varies from 68%to 78%during high-flow years,from 66%to 75%during moderately dry years,and from 61%to 70%during drought years.These findings comply with current control requirements in the Yangtze River Basin,demonstrating good practical feasibility.