基于面平均雨量误差修正的实时洪水预报修正方法

空间集总式水文模型的洪水预报精度会受到面平均雨量估计误差的严重影响.点雨量监测值的误差类型、误差大小以及流域的雨量站点密度和站点的空间分布都会影响到面平均雨量的计算.为提高实时洪水预报精度,本文提出了一种基于降雨系统响应曲线洪水预报误差修正方法.通过此方法估计降雨输入项的误差,从而提高洪水预报精度.此方法将水文模型做为输入和输出之间的响应系统,用实测流量和计算流量之间的差值做为信息,通过降雨系统响应曲线,使用最小二乘估计原理,对面平均雨量进行修正,再用修正后的面平均雨量重新计算出流过程.将此修正方法结合新安江模型使用理想案例进行检验,并应用于王家坝流域的16场历史洪水以及此流域不同雨量站密度的情况下,结果证明均有明显修正效果,且在雨量站密度较低时修正效果更加明显.该方法是一种结构简单且不增加模型参数和复杂度的实时洪水修正的新方法.

Real-time flood forecast updating method based on mean areal rainfall error correction

The accuracy of flood forecasts generated using spatially lumped hydrological models can be severely affected by errors in the estimates of mean areal rainfall. The quality of the latter depends both on the size and type of errors in point-based rainfall measurements, and on the density and spatial arrangement of rain gauges in the basin. Here, we use error feedback correction, based on the rainfall system response curve method, to compute updated estimates of the rainfall inputs. The capability of the method to improve the accuracy of real-time flood forecasts is demonstrated using the Xin''anjiang (XAJ) model applied to 16 flood events of the Wangjiaba Basin. The result shows that the forecast improvement is significant. For the Wangjiaba Basin, we also examinethe performance of the method for different rain gauge densities, and find that forecast improvement is more significant when gauge densities are lower. The method is relatively simple to apply and can improve the accuracy of real-time model predictions without increasing either model complexity and/or the number of model parameters.