纳希瞬时单位线参数优化研究

Study of Optimization of Nash Instantaneously Unit Hydrograph

应用矩法推求的纳希瞬时单位线参数还原同次洪水过程存在着与实测洪水过程拟合效果不佳的现象.根据实际洪水预报中对洪峰流量处预报精度要求较高的需要,构建了优选瞬时单位线参数的最优化模型,提出了应用矩法与梯度搜索法联合求解最优化问题的一套方法,并将矩法与该方法用于同场次暴雨洪水过程计算,计算结果表明,采用本优化模型及解法得出的结果较矩法预报精度有了进一步的改善,且在洪峰中具有较好的还原效果.研究表明优选瞬时单位线参数的最优化模型以及求解方法较之矩法更能得出符合流域汇流特性的单位线参数.

It has poorly fitting phenomenon when restoring the same flood using Nash instantaneous unit hy- drograph with moment method to calculate its parameters. This paper establishes an optimization model for selecting the parameters of Nash instantaneous unit hydrograph based on the actual needs of high forecast ac- curacy of flood peak, and bring up a method which can solve and optimize model with the moment method and gradient search method. Meanwhile, the paper uses the two instantaneous unit hydrographs which are derived by moment method and optimization model calculation the same flood. The results indicate that the forecast accuracy of the optimization model is better than that derived by moment method; and the first method has the better restoring effect at the flood peak. The study indicates that the optimization model and the solution method proposed can get the better instantaneous unit paragraph parameters to reflect the basin confluence characteristics.