Design flood revision for the upper Huaihe River Basin based on SWAT model

Abstract

变化环境下洪水序列的一致性遭到破坏，引发基于统计原理计算的设计洪水可靠性下降，亟需开展非一致性条件下的设计洪水修订研究.以淮河上游流域为研究区域，运用Pettitt检验法和滑动t检验法综合检测年最大洪峰流量序列突变点，在此基础上，采用SWAT分布式水文模型对变异前的洪峰与洪量序列进行还现，利用径流深的模拟结果修订设计洪水，并对修订后的洪水序列进行频率分析.结果表明：（1）淮河上游息县和淮滨站年最大洪峰流量呈现不显著的减小趋势，王家坝站则表现出不显著增加趋势，1991年为各站年最大洪峰流量序列的突变点；（2）3个水文站率定期和验证期的确定性系数（R²）和Nash-Sutcliffe效率系数（NSE）均满足适用性要求，其中流域出口王家坝站率定期R²、NSE分别为0.77和0.79、验证期分别为0.72和0.74，模拟精度较高；（3）淮河上游流域洪水设计值较修订前略有减小，其中，洪峰流量减小幅度平均值在3.3%~6.1%之间，淮滨站的减小幅度最大；不同时段洪量的减小幅度平均值在1.4%~2.7%之间，整体修订幅度小于洪峰流量的修订幅度，并且洪量的时段越长，修订幅度越小；随着重现期的增大，各洪水指标的修订幅度逐渐减小.本研究对于变化环境下的淮河流域水利工程规划和防洪减灾具有重要意义.;The consistency of flood series under changing environment is destroyed, which causes the decrease of reliability of design flood calculated based on statistical principle. Therefore, it is urgent to study the design flood revision under inconsistency conditions. Taking the upper Huaihe River Basin as the study area, Pettitt test and moving t-test were used to detect the abrupt change point of the annual maximum peak discharge series. The SWAT distributed hydrological model was applied to restore the series of peak discharge and flood volume before the breakpoint. Based on the simulation results of runoff depth, the design flood was revised, and the revised flood series frequency was analyzed. The results showed that:(1) The insignificant downward trend in annual maximum peak discharge was observed at Xixian and Huaibin Stations in the upper Huaihe River, while an insignificant upward trend was found at Wangjiaba Station. For annual maximum peak discharge, change point at three stations was detected in 1991. (2) The certainty coefficient (R²) and Nash-Sutcliffe efficiency coefficient (NSE) from the three hydrological stations met the applicability requirements. The R² and NSE of the Wangjiaba Station during the calibration period were 0.77 and 0.79, respectively, and the R² and NSE during the validation period were 0.72 and 0.74, respectively, indicating that the simulation accuracy was high. (3) The design flood value from the upper Huaihe River Basin decreased slightly compared with that before the revision. The average decline rate of annual maximum peak discharge was from 3.3% to 6.1%, and the largest decrease rate was found at Huaibin Station. The average decline range of flood volume during different periods was between 1.4% and 2.7%, and the overall revision range was smaller than that of peak discharge. Moreover, the longer the duration of flood volume, the smaller the revision range. With the increase of the recurrence period, the revision range of each flood index decreased gradually. This study is of great significance to the planning of water conservancy projects and flood control and disaster reduction in the Huaihe River Basin under changing environment.