考虑非均匀暴雨中心空间分布的洪水预报方法

The Flood Forecasting Method Considering the Spatial Distribution in the Inhomogeneous Rainstorm Center

在洪水预报实践中,降雨在流域空间分布的不均匀性一直是影响预报精度的主要问题之一,这一问题在我国半湿润、半干旱及干旱地区尤为突出。本文提出了一种针对非均匀暴雨空间的洪水预报方法,按照非均匀暴雨中心的空间分布,可以将流域划分为“暴雨核心区”和“非暴雨核心区”,分别采用不同的水文模型参数进行产汇流计算。该预报方法可充分利用流域内各雨量站在暴雨期间的雨量分布信息,考虑降雨开始时土壤含水量在流域上的差异,方法简单,易于操作。方法中提出的降雨不均匀系数能定量有效地判断流域内发生不均匀降雨的临界点,有助于准确判断该预报方法在实际预报中的使用时机。实践证明,该方法可以减少在降雨不均匀情况下选择模型参数的不确定性,与传统方法相比能有效提高洪水预报精度。

In the practice of flood forecasting,the inhomogeneous rainfall distribution is one of the main problems affecting the forecasting accuracy.The problem is especially prominent in semi-humid,semi-arid and arid area of China.The flood forecasting method proposed by this study aims at improving the forecasting accuracy of floods caused by inhomogeneous rainstorms.Based on the spatial distribution of the storm center,the river basin is divided into a“storm core area”and a“non-storm core area”,and different runoff generation and concentration parameters are adopted for the two areas during the rainfall-runoff modeling.The method is simple and easy to operate,which takes full advantage of the rainfall information measured by rain gauges and considers the spatial diversity of the soil water at the beginning of the storm.The proposed rainfall inhomogeneous coefficient can help determine the critical time of the storm occurrence so as to tell when to initialize the flood forecasting method.A case study shows that using the forecasting method can largely reduce the parameter uncertainties when dealing with the inhomogeneous storms and effectively increase the flood forecasting accuracy compared with traditional methods.