基于基流退水过程的非一致性枯水频率分析

枯水流量频率研究在水资源管理中具有重要作用。在气候变化和人类活动的影响下,水文极值序列的频率分布随时间变化。近年来,非一致性水文系列频率分析作为一项新课题逐渐被水文学者重视和研究。非一致性序列的频率计算方法主要集中于洪水和年径流,而对枯水频率研究不足。本文探讨了流域基流退水和降雨特征对河道枯水流量的重要影响,并通过结合基流退水分析和广义回归模型,研究了基于基流退水过程的非一致性枯水频率分析方法。以渭河为实例,结果表明:以流域退水参数和降雨参数为协变量的非一致性模型更好地描述了渭河华县站枯水流量分布特征的变化;渭河华县站枯水流量总体呈减少趋势,主要原因是基流退水速率加快、日平均降雨深减少以及降雨事件平均时间间隔增加。研究成果对变化环境下水资源供水设计管理、河流生态系统保护以及旱灾风险管理等问题具有实践意义。

Nonstationary frequency analysis of low-flow series considering both baseflow recession process and rainfall

The frequency analysis of low flows plays a key role in water resources management and planning. Due to the influence of climate change and human activities, the frequency spectrum of extreme hydrologic events would have changed over time. In order to implement hydrological frequency analysis under the changing environments, many nonstationary frequency analysis techniques have been developed recently. However, these methods are put forward mainly for analysis of floods rather than low flows. In this paper, a method incorporating the information of base-flow recession and rainfall into the nonstationary frequency analysis of low-flow series is carried out. The analysis presented in this study is based on 50 years of daily rainfall-runoff data from Huaxian gauging station of the Weihe River of northwestern China. The result shows that the method that establishes the link of low flows to base-flow recession process and rainfall is able to describe the frequency evolution of nonstationary low-flow series better than the method of trend analysis, thus providing important guidance to develop better techniques for the low-flow frequency analysis.