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。点雨量测量值的误差类型、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,这种误差的影响在雨量站个数较少的大流域尤为明显。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。此方法将水文模型作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作为信息,通过降雨系统响应曲线,采用最小二乘估计方法,对面平均雨量进行修正,再使用修正后的面平均雨量重新计算出流过程。将此修正方法与新安江模型相结合,首先使用理想案例进行检验,然后将此方法应用于浙江富春江流域实时洪水预报中,通过2010—2014年间的14场历史洪水的应用检验,结果表明该方法具有明显修正效果,是一种结构简单、不增加模型参数且不改变预报模型结构的实时洪水预报修正的新方法。
The accuracy of flood forecasts obtained from spatially lumped hydrological models is highly affected by the uncertainty in the estimates of area-mean rainfall that depend on the error type and magnitude of rain gauges and their density and pattern of space distribution. The effect of these errors is more prominent in a large basin with a small number of rainfall gauges. To improve the accuracy of real- time flood forecasting, we herein describe an updating method for area-mean rainfall estimation using rainfall system response curves. This new method takes a hydrological model as a response system between input and output, and updates the area-mean rainfall using the rainfall system response curves and least square method to minimize the error between the observed and simulated flow series. Then, the stream flow is recalculated using the updated area-mean rainfall series. Application of the method is demonstrated in combination with the Xinanjiang model tests, via a synthetic case and 14 historical flood events that occurred in the Fuchunjiang basin in Zhejiang during 2010-2014. The results show that the method can significantly improve the accuracy of real-time flood forecasts without increasing model structure complexity or the number of model parameters.