北京山区暴雨泥石流预警模型研究

Research on early warning of storm debris flow in Beijing mountain area

北京山区泥石流多以暴雨类沟道侵蚀型泥石流为主,具有暴发频率低、间歇周期长、群发性显著等特点,在无丰富泥石流事件支持的情况下,泥石流预警一直是个难题。在北京地区已有泥石流预警模型校验的基础上,以泥石流流域降雨精细监测为基础,将场次累计降雨量(R)和最大小时雨强(I)视为反映暴雨泥石流雨场特征的二维离散随机变量,分析了不同雨场累计降雨量(R)和最大小时雨强(I)的联合概率分布特征,绘制了降雨安全等概率线;在此基础上,以近年来少数泥石流样本为基础,以降雨安全概率4%曲线作为北京地区泥石流预警线。研究结果表明:当雨强大于60 mm/h,过程雨量达到220 mm时,泥石流发生的可能性极大,可满足现有地质环境背景下暴雨泥石流预警需求,并可为无丰富泥石流灾害样本地区的泥石流预警提供技术参考。

Most debris flows in the mountainous areas of Beijing belong to channel erosion type,which have characteristics as low frequency,long intermittent cycle and massive developing.Without the support of abundant debris flow events,early warning of debris flow has always been a problem.In this paper,firstly,the accuracy of existing warning models for Beijing area were verified.Then,based on years of monitoring rain data,process cumulative rainfall(R)and maximum hourly rainfall intensity(I)were considered as two-dimensional discrete random variables,the joint probability distribution characteristics of rain fields were analyzed,and the probability line of rainfall safety of debris flow-free events were established.Finally,the rainfall safety probability 4%curve was set as the rainstorm debris flow early warning curve in Beijing mountain area based on a small number of debris flow samples.The results show that:when the process cumulative rainfall(R)reaches 220 mm and the maximum hourly rainfall intensity(I)is greater than 60 mm/h,the possibility of debris flow occurrence is greater.The proposed early warning curve can meet the needs of debris flow early warning with present geological conditions and provides a technical reference for the establishment of early warning models in areas without abundant debris flow events.