基于起涨流量的东南沿海流域洪水预报方法

A study on the method of flood forecasting based on initial discharge in the southeast coastal watershed

应用HEC-HMS模型模拟船场溪流域历史9场典型洪水,分析起涨流量和初损值两个与前期降雨密切相关参数的定量关系,以此为基础,根据河道实测起涨流量推算初损值,从而实现考虑流域前期降雨影响的洪水预报;并通过起涨流量变化来模拟分析前期降雨变化对洪水过程的影响。研究表明:(1)HEC-HMS模型能够较精确模拟船场溪流域场次洪水过程,其中对于暴涨洪水和双峰洪水模拟效果较差。(2)起涨流量和初损两个参数成对数关系,决定系数R2达0.95,3场洪水的验证结果也较好,未来可以利用次洪发生前河道起涨流量推求初损值,并以气象部门降雨预报为驱动实现洪水预报。(3)前期降雨变化对峰现时间影响小,但对洪峰流量具有显著的影响:在前期降雨较小时,其降雨的增多会导致洪峰流量迅速增加,随着前期降雨的不断增加,这种影响逐渐减小。另外,对于双峰洪水,前期降雨变化主要对第一个洪峰产生影响,对第二个洪峰影响则较不显著。

The objective of the research is to study on the method of flood forecasting considering the impact of antecedent precipitation,and with its convenience when used.Based on HEC-HMS model,twelve flood events were used to calibrate the model,and a functional relationship between initial discharge and initial loss was established.The initial loss could be computed based on the initial discharge using the functional relationship for the flood forecasting,which consider the antecedent precipitation.In addition,the impacts of antecedent precipitation change on flood events were simulated based on the HEC-HMS.The results showed as following:(1)The HEC-HMS model was reliable representation of flood processes and the performance for flash floods and double peaks floods was much poor.(2)There was a very marked logarithmic relationship between initial discharges and initial losses,it is because that the R 2 was 0.95 and the performance of 3 validated flood events was reliable,which indicated that the HEC-HMS model could be used to forecast flood events considering the antecedent precipitation based on the logarithmic relationship.(3)The change of antecedent precipitation have a little influence on the time of flood peak,but have a significant effect on peak discharge,and the effect will decrease with the increase of antecedent precipitation.Moreover,the impact of antecedent precipitation on the first flood peak was significant,but not significant on the second flood peak.