三峡水库入库洪水分析计算研究

Analysis of Inflow Floods of the Three Gorges Reservoir

摘要: 三峡水库建成蓄水后，水库周边区间流域产汇流条件发生改变，新形成的入库洪水较天然条件下的坝址洪水具有“洪峰增大，涨水段洪量增大”等特性。本文基于多输入单输出系统模型模拟计算三峡建库前的入库流量系列，定量分析了三峡入库与坝址的年最大洪峰、3、7、15 d洪量之间的关系，整编得到三峡入库流量不连续序列，据此开展三峡入库洪水频率分析，并与坝址计算成果进行比较。结果表明，入库系列与坝址系列的洪峰以及3 d、7 d洪量差异明显，15 d洪量变化不大，入库百年一遇设计洪峰较坝址设计洪峰增大7.89%，入库百年一遇3 d、7 d、15 d洪量较坝址设计洪量分别增大5.49%、2.52%和0.31%，现状条件下采用入库洪水设计值作为三峡水库防洪调度的科学依据更为合理。

Abstract: The runoff generation and confluence conditions at intervener basin have been changed after the com-pletion of the Three Gorges Reservoir (TGR). Since the reservoir inflow has higher peak with larger flood volume in the rising limb compared to the floods at dam site, the original designed flood results at dam site can no longer satisfy the current requirement of operation and management for TGR. In this paper, a multiple inputs and single output linear system model was built to calculate the historical reservoir inflow series and then linear regressions were used to determine the quantitative relations of flood peaks, 3 d, 7 d and 15 d flood volumes between inflow series and flood series at dam site. Subsequently, the simulated inflow series combined with historical floods were obtained and used for inflow frequency analysis. Comparing the inflow frequency analysis results with the existing design flood at dam site, the flood peaks and 3d, 7 d flood volumes are increased significantly, while the change of 15 d flood volume is not evident. It is shown that 100-year designed inflow peak discharge, 3 d, 7 d and 15 d inflow volumes are 7.89%, 5.49%, 2.52% and 0.31% larger than those of designed floods at dam site, respectively. Therefore, it’s more rational to take the designed inflow floods as scientific bases for TGR reservoir operation and management.