无资料小流域设计洪水不确定性研究

Estimating Uncertainty in Design Flood for Ungauged Catchments

针对小流域降雨资料不足甚至无降雨资料的情况,研究了在不同雨型(主雨位偏前、偏中和偏后)下,使用2种暴雨频率计算方法(地区综合法和L-矩法),计算不同重现期设计暴雨和设计洪水的不确定性。结果表明L-矩法的计算结果不确定性小,更稳定,而地区综合法偏保守;不同雨型下的设计洪峰和洪水历时变化较小,但峰现时间相差较大,会极大地影响调洪结果。

Estimating design flood in ungauged catchments is difficult due to data scarcity. Two methods, regional synthetic method and L-moment, are used to calculate design rainfall depths, and thus to estimate design flood. Also, three different 24-hour-hyetographs are considered, with front-, mid-, back- located peak rainfall. A small ungauged catchment in Zhejiang Province is used as an example here and results show that the regional synthetic method is more conservative than L-moment and contains more uncertainty. Delicate peak change discharge for different hyetographs can be observed while peak times are different, which is believed to affect reservoir routing significantly.