基于SWMM的暴雨强度公式极值样本分析

Extreme sample analysis of rainstorm intensity formula based on SWMM

为了研究极值降雨样本对暴雨强度公式的影响,提高暴雨强度公式推求的合理性,基于北京市1941—2008年降雨数据,利用年最大值法取样,分析极值降雨样本的存在对频率分析、公式推求的影响,发现极值雨量会使得频率分布曲线在高重现期区段有所上升,从而导致暴雨强度公式结果偏大。并构建SWMM(Storm Water Management Model)模型,针对不同暴雨强度公式推求的设计雨型进行模拟,分析不同暴雨强度公式对管网溢流水量的影响。研究结果表明:与传统方法相比,可以考虑采取以年次大值样本取代极值样本来处理极端降雨事件。该方法既考虑了降雨样本数据容量的整体性,也避免了极值降雨对暴雨强度公式产生的不利影响。对极值降雨样本进行处理之后得到的暴雨强度公式更加合理,可以避免使用公式所造成的设计排水能力偏大,避免管网建设中的浪费。

In order to study the influence of extreme rainfall sample on rainstorm intensity formula,and improve the rationality of the rainstorm intensity formula,based on the rainfall data of Beijing from 1941 to 2008,this paper analyzes the influence of the existence of extreme rainfall sample on frequency analysis and formula inference by using the annual maximum method,and finds that the extreme rainfall will make the frequency distribution curve increase in the high reproducible period,which leads to a large result of the storm intensity formula.The SWMM(Storm Water Management Model)model is constructed to simulate the design rain pattern derived from different rainstorm intensity formulas,and analyze the influence of different rainstorm intensity formulas on pipe network overflow.The results show that compared with the traditional method,it is necessary to consider replacing the extreme value sample with the second largest annual rainfall sample to deal with extreme rainfall events.This method not only considers the integrity of rainfall sample data capacity,but also avoids the adverse effects of extreme rainfall on the storm intensity formula.The rainstorm intensity formula is more reasonable.It can avoid the excessive design drainage capacity,and the waste in the construction of the pipe network can be avoided.