基于水域面积法的山区河流水电站下游生态流量定值研究

水电站的大量兴建导致下游河道萎缩退化甚至断流,如何改变水电站运行调度方式,维持下游河道一定的生态流量、保障河流健康成为国内外普遍关注的问题.本文在传统水文学方法的基础上融入生物栖息地法思想,以河流生态系统的生物多样性为功能目标,用河道流量反映河流的水文过程,河道水域面积反映河流生态系统的生物多样性,创新性地提出考虑河道水文生态特性的生态流量定值方法——水域面积法.以北江上游浈江二级支流罗坝水为例进行分析计算.计算结果表明:枯水年罗坝水生态流量为2.26 m3·s-1,占多年平均流量的25.97%;平水年生态流量分月控制,生态流量过程与建站前流量过程基本一致.根据枯水年的生态流量值和平水年各月份的生态流量值,结合水电站的运行调度规则,换算成一定时期内的径流量来确定该时期内水电站需释放的水量,进而对水电站下游河道的生态功能进行保护和修复.

Calculation of ecological flow setting for hydropower stations of mountainous river based on water surface area method

Widespread construction of hydropower stations has led to shrinkage or even cutoff in the downstream river channels. How to change the operation rule of hydropower stations, maintain certain ecological flow in the downstream river channels, and guarantee the river health have drawn great attention. This study integrates the biological habitats thoughts based on the traditional hydrology method, and takes the river ecosystem biodiversity as function goal. An ecological flow setting calculation method- water surface area method is proposed which considers the river ecological and hydrological features. This method uses the discharge to reflect the river hydrological processes and water surface area to reflect the ecosystem biodiversity respectively. By taking Luoba River, a secondary tributary of Zhenjiang River (the upper reaches of Beijiang River) as an example, we show that the ecological flow of Luoba River is 2.26 m³ · s^-1 in low flow year, accounting for 25.97% of the average annual discharge. In median water year, the ecological flow is on monthly control and the ecological flow process is consistent with the flow process before the establishment of hydropower stations. Afterwards, in consideration of hydropower station operation scheduling rules, we convert the ecological flow in normal and low flow year to the a certain period of runoff to determine water volume the hydropower stations needed to release in this period. We may therefore reach the target of protecting and restoring the ecological functions in the downstream channel of the hydropower stations.