基于雷达估测降雨及WRF-Hydro模型的典型山洪模拟研究

Simulation Study of Typical Flash Floods based on Radar-Estimated Rainfall and WRF-Hydro Model

受复杂地形与基础气象水文资料缺乏限制,山区小尺度流域的水文预警预报技术较为薄弱,利用高分辨率雷达观测资料驱动分布式水文模型是提高山区小流域洪水预报性能的有效途径之一。本文以位于重庆中部的山区小流域二河流域为研究区域,开展基于雷达估测降雨数据的WRF-Hydro模型在山区小流域的山洪模拟研究,以评估雷达估测降雨的水文应用效果和WRF-Hydro模型在山区小流域的适用性。选取流域内典型的暴雨洪水过程,利用S波段的多普勒天气雷达的估测降雨数据驱动WRF-Hydro模型,并结合新安江模型进一步对比分析模拟效果。研究结果表明:(1)在二河流域,采用雷达估测降雨数据驱动WRF-Hydro模型,可以较好地模拟洪水过程、洪水流量以及峰现时间,纳什效率系数高于0.65,克林-古普塔效率系数高于0.50,相关系数高于0.85。(2)将WRF-Hydro模型与新安江模型进行比较分析,在二河流域,WRF-Hydro模型的模拟效果优于新安江模型,纳什系数差值0.03,相关系数差值为0.04,进一步表明WRF-Hydro模型在山区小流域较优的洪水模拟性能。总体而言,基于雷达估测降雨数据的WRF-Hydro模型在二河流域表现出了良好的模拟洪水的性能,可进一步在类似小尺度山区流域进行应用研究。

Limitations of complex topography and lack of basic meteorological and hydrological information make the hydrological early warning and forecasting technology in small-scale mountainous watersheds weak.Using high-resolution radar observations to drive distributed hydrological models is one of the effective ways to improve the flood forecasting capabilities in small mountainous watersheds.Focusing on the Erhe river basin located in central Chongqing as the study area,a study of WRF-Hydro model flash flood simulation based on radar-estimated rainfall data is carried out to evaluate the hydrological application effect of radar-estimated rainfall and the applicability of WRF-Hydro model in small mountainous watersheds.The typical storm flood process in the watershed was selected,and the WRF-Hydro model was driven by the estimated rainfall data from S-band Doppler weather radar,and further compared with the XAJ model to analyze the simulation effects.The results show that:(1)the WRF-Hydro model driven by radar-estimated rainfall data provides a better simulation of the flood process,flood flow and peak-to-peak time in the Second River Basin,with the Nash efficiency coefficient above 0.65,the Kling-Gupta efficiency coefficient above 0.50 and the correlation coefficient above 0.85.(2)Comparing the WRF-Hydro model with the XAJ model,the simulation effectiveness of the WRF-Hydro model is superior to that of the XAJ model in the Erhe River basin,with a difference of 0.03 in the Nash coefficient and 0.04 in the correlation coefficient,further indicating the superior flood simulation performance of the WRF-Hydro model in small mountainous basins.Overall,the WRF-Hydro model based on radar-estimated rainfall data exhibited satisfactory flood simulation performance in the Erhe basin,and can be further applied in similar small-scale mountainous basins.