迟滞瞬时单位线参数估计熵法

Parameter estimation for lag-instantaneous unit hydrograph with entropy method

迟滞瞬时单位线的数学表达式形同于皮尔逊Ⅲ型分布,基于数学相似性原理建立了两者参数之间的关系。以信息熵理论为基础,构造了参数估计方程,然后将对数均值用泰勒级数展开,忽略高阶项,提出了迟滞瞬时单位线参数估计的一种方法--熵法。从检验的算例估计实值的精度来看,熵法其结果令人满意,精度比常用的矩法估计值有明显提高,从而表明提出的方法具有良好的参数估计效果。

The mathematic expression of lag - instantaneous unit hydrograph is similar to Pearson type Ⅲ distributioncurve. In accordance with the principle of mathematic similarity, the parameter relation between two methods was established.Based on information entropy theory, the parameter estimation function was established, then logarithmic average value was de-veloped by Talyor's series with the high - order terms neglected, and a parameter estimation method of lag - instantaneous unithydrograph, entropy method, was suggested. The accuracy of estimated parameter values in example shows the results of entro-py method are satisfactory and the accuracy is significantly improved compared with moment method. It is shown that the sug-gested method possesses good parameter estimation effect.