水布垭枢纽设计洪水研究

Study on design flood for Shuibuya Hydropower Station

水布垭库区汇水面积占坝址以上汇水面积的７３％，水库建成后回水区内原有的产、汇流条件均会发生变化。因此，在设计洪水计算中除坝址设计洪水外，还分析了入库设计洪水和可能最大洪水。坝址设计洪水采用频率分析法计算，选择了１９６８、１９６９、１９９７年洪水作为设计洪水典型。入库洪水根据资料情况采用典型年法，并用多种方案分析比较。典型年选择与坝址设计洪水一致，入库洪水比坝址洪水峰现时间一般提前３～６ｈ，洪峰倍比在１．１３～１．２６，２４ｈ洪量倍比在１．０２～１．１３之间，借用各典型年坝址设计洪水的放大倍比放大典型年入库洪水过程，得到入库设计洪水过程。可能最大暴雨采用暴雨移置和时面深概化２种方法４个方案进行估算，并用净雨差值法推算可能最大洪水。

The intermediate drainage area between damsite and the end of Shuibuya reservoir is up to 73% of the total drainage area above damsite, and the runoff producing and confluence condition after the reservoir is constructed will change. Therefore, not only design flood at damsite but also design flood of reservoir inflow and possible maximum flood are analysed. The design floods at damsite are computed by frequency analysis method and the floods in 1968,1969,1997 are selected as typical cases. In the light of available data, the reservoir inflow floods are computed by typical years method and compared with various analysis methods. The selected typical years are identical with those of design flood at dam site. The occurrence time of reservoir inflow flood peak is 3～6 hours earlier than that of flood peak at damsite, with flood peak discharge ratio 1.13 ～ 1.26 , flood volume ratio 1.02 ～ 1.13 . Through amplifying reservoir inflow flood hydrograph by using amplification factor of design flood at damsite, the reservoir inflow design flood hydrographs are obtained. The possible maximum storm is estimated by 4 schemes with storm transposition method and time depth generalization method, and the possible maximum flood is computed by differential value of net rain depth.