生态水力学法在河段最小生态需水量计算中的应用

Application of the Eco-hydraulics Method in Calculation of Ecological Flow of River

以雅砻江锦屏二级水电站建成后造成坝后119 km的减水河段为例,用生态水力学法计算了减水河道最小生态流量,得出为满足减水河段鱼类的生存及繁衍,枯水季节猫猫滩闸址处必须保证下泄45 m3/s流量,在该流量下,锦屏二级水电站减水河段中95%左右河段水深、流速、水面宽、湿周率、过水断面面积、水面面积等水力因子可满足河道内鱼类的生存繁衍;水温的变化不会影响河道内鱼类的产卵;鱼类适应的缓流、急流、浅滩、深潭等水力形态的位置发生变化,数量保持不变。总的来说,水生生物的生物量将随着河道流量的减小而减少,但种群数量将保持不变。该实例为生态水力学法计算河道最小生态需水量做了一些探索性的研究工作。

The lowest ecological water demand in the 119 km reducing reach of Yalong river downstream of Jinping waterpower station stagell （Jinping Ⅱ） as an example is studied by the method of eco-hydraulics. The results indicate that the lowest ecological discharge in the reducing reach in the dry season is 45 m^3/s in order to meet the subsistence of fish. In the condition of 45 m^3/s river flow, the 95% river channels can satisfy the hydraulic factors for the subsistence of fish. These hydraulic factors include 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 place of hydraulic form, which includes torrent, subcritical flow, riffle, deep pool will change, but their amount remains above the same in 45 m^3/s. Generally speaking, as the reduction of river discharge, the biomass will reduce. However, the amount of animal community will remain as long as the river discharge exceeds 45 m^3/s. This example severs as an exploring work in calculating ecological based on flow in river channels.