一种优化混合式电站生态流量过程的模式

A Model for Optimizing Ecological Flow Regime of Dam-diversion Type Hydroelectric Station

针对采用传统生态基流量计算方法所确定的流量难以兼顾生态效益和经济效益的难题,提出了一种适宜于混合式水电站的生态流量过程的优化模式。以栖息地加权可用面积为决策指标,认为优化前后基流量所对应加权可用面积相同时河道生境不发生较大改变,通过优化天然河道生境不适区的方式调整引水比使生态经济效益达到联合最优。以昌波水电站为例,选取长丝裂腹鱼为保护目标,利用丁坝对减水河道生境不适区进行优化,结合目标水生生物繁殖敏感期对水力生境的需求,重点研究了生境不适区的水文情势变化情况并确定了优化后的全年河道生态流量过程。结果表明:当选取3个生境不适区进行优化时,河道生态基流量为多年平均流量的10%,所对应的栖息地加权可用面积为87 782.02 m^2,而传统方法所得的基流量为多年平均流量的20%,所对应的栖息地加权可用面积为87 726.2 m^2。在保证水力生境条件不变的情况下,前者的流量比后者降低了10%。依据优化后所得生态基流量及对河道涨落水率的研究结果推求得到的昌波水电站生态流量过程,在满足目标鱼类生存繁殖所需水量的同时,较好地保留了天然栖息地的径流涨落变化和流量脉冲过程,为营造保护鱼类适宜生境和确定优化混合式电站生态流量过程提供了示范,同时为电站的生态调度管理提供了依据。

Aiming at the problem that the flow determined by the traditional ecological basic flow method is difficult to consider both the ecological and economic benefits,in this paper we propose an optimization model suitable for the ecological flow process of the dam-diversion type hydroelectric station.This model adjusts the diversion radio by optimizing the vulnerable areas of hydraulic factors in natural river channels to make the ecological and economic benefits reach the joint optimum,in which the WUA is adopted as the decision index and a hypothesis is assumed that the fish habitat does not change greatly if the WUA of improved ecological base flow keeps in line with that before improvement.Taking the Changbo Hydropower Station for example,this paper emphasized on the changes of hydrological regime in the vulnerable areas of hydraulic factors and the improved ecological flow process of the river channel was determined after considering the fish of Schizothorax dolichonema＇s requirement for the hydraulic factors in its spawn- ing period when the vulnerable areas were optimized through using the spur dike.The results showed that when selected 3 vulnerable areas to optimize,the river ecological base flow is 10% of the average annual flow while the calculation results of traditional methods is 20%,the two corresponding effective area is 87 782.02 m^2 and 87 726.2 m^2 respectively.The former flow rate was decreased by 10% compared with the latter under the condition that the habitat＇s hydraulic condition remained unchanged.The ecological flow process of Changbo Hydropower Station which could preserve the basis of the optimized ecological fluctuation of runoff and process of flow pulse while satisfying the water demand of target fish is obtained on the basis of the optimized ecological base flow and the study results of rise rate and fall rate.This process provides a demonstration for the establishment of appropriate hydraulics habitat for protected fish and the optimization of the ecological flow regime of mixed type hydropower stations.Meanwhile,it also provides a basis for the ecological dispatching management of power station.