雅砻江锦屏二级水电站减水河段生态需水量研究

针对雅砻江锦屏二级水电站减水河段面临的水生生物生态需水问题，提出了计算河道最小生态基流量的生态水力学法，考虑了水力生境参数的全河段变化情况，计算结果避免了单凭最低值进行判断所造成的判断失误。确定了锦屏二级水电站减水河段鱼类对流速、水深、水面宽等水力生境的需求。通过河道水力模拟，得出为满足减水河段鱼类的生存及繁衍，必须保证枯水季节猫猫滩闸址下泄45 m3/s流量，在该流量下，锦屏二级水电站减水河段中95%左右河段水力因子可满足研究中提出的河道内鱼类的生存条件；水温的变化不会影响河道内鱼类产卵；鱼类适应的缓流水、急流水、浅滩、深潭等水力形态的位置虽然发生变化，但数量保持不变。

ECOLOGICAL WATER DEMAND OF REDUCING REACH OF YALONG RIVER DOWNSTREAM OF JINPING WATERPOWER STATION STAGE II

The authors proposed the eco-hydraulics in calculating the lowest ecological flow in river channels to resolve ecological water demand of Jinping Waterpower Station Stage II(Jinping II) reducing reach.The lowest ecological flow in river channels was determined by satisfying hydraulic habitat of objective(aquatic) biology.The change in hydraulic habitat parameters in whole reducing reach was considered and the conception of the percentage of cumulated river length to the reducing reach length in fulfilling the hydraulic habitat parameters was put forward.The gained results avoid the misjudgment conduced by using lower parameter value when the percentage of the length of reducing reach to the total is very small.Referring to the characterization of hydraulic habitat parameters in related literature,using specific situation of fish habitat in Jinping II reducing reach of Yalong River,the authors confirmed the fish habitat requirements to various hydraulic parameters,such as velocity,water depth,water surface width etc.It is indicated that the lowest ecological discharge in the reducing reach in dry seasons is 45 m~3/s in order to meet the subsistence of fishes.95 percentage of river channels can satisfy the hydraulic factors for the subsistence of fishes,including water depth,velocity,water surface width,wetted perimeter ratio,cross section area,and water surface area.The change of water temperature will not affect fish spawning in 45 m~3/s.The places of hydraulic forms including torrent,sub-critical flow,riffle and deep pool will change,yet their amount will remain the same as in 45 m~3/s.When the river discharge reduces,the biomass will reduce.However,the amount of animal community will remain as long as the river discharge exceeds 45 m~3/s.This method provides feasible means to determine the flow for ecological requirement of fishes in river channels.