东江水库调节对其下游各级水库淹没的影响

Effect of Dongjiang reservoir on reducing the inflow flood of downstream cascade reservoirs

河流梯级开发中，上游有龙头水库时，对下游调节作用较大。如湖南省东江水库系一大型多年调节水库，调节系数为１．３。考虑利用该库空闲库容容纳洪水，减少下泄流量，与区间洪水组合后，下游各梯级设计洪水在洪水标准低于３０年一遇时，其值比原设计小，相应回水降低，淹没损失减少。以东江下游乔口～遥田７个梯级为例，其中乔口、石面坦、程江口、永兴、上堡等５梯级减少的淹没损失是原各梯级淹没损失的７８．７２％。经济效益显著。

In cascade development of a river,an upper large reservoir has a considerable regulation funcfion to lower cascade reservoirs. For example, Dongjiang reservoir in Hunan Province is a multi-annual regulating reservoir with its regulation coefficient of 1. 3. The free capacity of the reservoir would be utilized for flood retention to decrease its outflow.Then, when criterion of flood control is less than 30 year flood, the downstream cascade reservoirs' inflows which will formed by c.mbinati.n of decreased out flow and every local flood would be less than original respective design flood inflows respectively, resulting in a backwater drop and a decresae in inundation loss. Taking seven cascades between Qiaohou and Yaotion downstream from Dongjiang as an example the decrease in inundation losses of the five cascades: Qiaokou, Shimiantan, Chengjiangkou, Yongxing and Shangbao amounts to 78. 72 percent of the original inundation losses of the cascades. The economical benefit from this is remarkable.