地区线性矩法估算的暴雨频率设计值空间连续性问题探讨

Study on Spatial Continuity of Precipitation Quantile Estimates Based on Regional L-moments Analysis

地区线性矩法(Regional L-moments Analysis,RLMA)是目前最先进的频率估算方法之一,自20世纪90年代起被广泛应用于美国及其他一些国家的防洪设计标准的分析计算中;我国近年也在太湖流域暴雨频率分析中成功地采用推广了这一水文气象途径的频率计算方法,积累了实际经验。但是,由于地面雨量站点有限、资料长度有限以及站点空间分布的不均匀等问题,研究区中相邻水文气象一致区之间暴雨频率估算值会出现空间不连续性的现象,这个空间不一致的问题尚没有得到合理的解决。在简要介绍地区线性矩法推求频率估计值的基础上,着重讨论并介绍一种概念清楚、简单易操作的基于空间往返二次内插的校正方法,来解决频率估算值空间不连续的问题。这种空间内插平差主要通过构造一个与研究区实测站点控制面积相应分辨率的虚拟网格站网来实现。研究结果表明,经过平差后校正的研究区内各站点的频率估计值的经验频率与理论概率更加接近,频率估计值的空间分布也更加合理。

Regional L-moments analysis （RLMA） is the most advanced method for hydrologic frequency analysis, which has been widely used for precipitation frequency analysis in the United States and some other countries since the 1990s. Recently in China, RLMA has been successfully applied to precipitation frequency analysis in the Taihu Lake Basin as a pilot study. However, due to the lack of the rainfall stations with sparse spatial distributions as well as the short data length, the precipitation quantiles show a spatial discontinuation between quantiles somewhere around some areas in between the homogeneous regions. This study mainly presents a meaningful and simple correction method based on spatial interpolation to solve the discontinuity by adjusting the draft quantiles. The annual maximum series at 96 stations with 20-year and longer of rainfall data from the Taihu Lake Basin in East- China were used for the study. The results of adjusted precipitation quantiles that had been obtained via the RLMA for the Taihu Lake Basin exhibit better reliablity expressed in relative error of the empirical frequency to the theoretical exceedance probability of the data, and a better spatial smoothing pattern shown as well.