基于随机雨型的山洪灾害预警模式

针对雨型随机性所导致山洪灾害预警预报空报、漏报率过高问题,为提升山洪灾害预警精度,依据概率分布传递扩散原理,以雨型特征参数为控制条件,提出了基于参数控制的随机雨型生成法,建立了基于随机雨型的山洪灾害临界雨量计算模型及考虑决策者风险偏好的预警模式。以裴河流域为例,对不同雨型集下的临界雨量进行对比分析,并确定研究区6h临界雨量阈值空间。结果表明:雨峰位置、峰值倍比、前期土壤含水量对临界雨量的影响范围分别为32%~34%、33%~34%、15%~22%;雨型较前期影响雨量对临界雨量影响幅度更大;由雨峰位置系数和峰值倍比(r,bmax)双因子雨型集所确定的6h临界雨量阈值空间为98~185mm;考虑决策者不同风险偏好的临界雨量预警模式合理可靠,对更合理地开展山洪灾害预警工作具有指导意义。

An early warning model for flash floods based on random rainfall patterns

The aim of this work is to confront the problem of the high rate of missed alarms for flash flood warnings and forecasts due to the random nature of rainfall. In order to improve the accuracy of flash flood warnings,considering the transmission and diffusion principle of probability distributions,and by taking the characteristic parameters of rainfall patterns as the control conditions,a random rainfall pattern method based on parameter control is proposed. In addition,a critical rainfall model of flash floods based on random rainfall patterns and an early warning model considering the risk appetite of decision makers are established. Taking the Peihe watershed in Henan Province,as an example,we performed a comparative analysis of the 6 h critical rainfall under different rain pattern sets,and determined the 6 h critical rainfall threshold space for the study area. The results are as follows:the influence ranges of the precipitation peak position coefficient (r),peak multiple ratio (b_max) and antecedent precipitation (P_a) on the critical rainfall are 32% to 34%,33% to 34%,and 15% to 22%,respectively;the rainfall pattern is found to have a greater impact on the critical rainfall than that of the antecedent precipitation;the 6 h critical rainfall threshold space determined by the double factors of r and b_max is 98 to 185 mm. Therefore,the critical rainfall warning model considering the different risk preferences of decision makers is effective,and has the potential for guiding the more reliable implementation of flash flood warning systems.