渭河流域上游枯水径流特征与机理分析

Features and mechanisms of low flow runoff in the upper reaches of the Weihe River

选取渭河干流及上游主要支流葫芦河、牛头河、藉河的秦安、社棠、天水、武山和北道5个水文站1956-2005年50 a逐月径流资料(社棠从1959年开始共47 a资料),利用传统概率统计法和时间序列分析法,对渭河流域葫芦河、牛头河、藉河3条支流和渭河干流的年最小枯水流量特征、月最小流量特征、枯水发生时间进行了分析,并从气象及人类活动两方面分析了枯水径流及极值的形成机理.研究表明:渭河流域上游年平均流量与多年平均最小流量的倍比较大,且下垫面越复杂,人类活动越频繁,最小流量受到的影响越大;最小月平均流量相比瞬时最小流量更为稳定;耕地面积与枯水径流呈负相关关系,不同时期、不同量级的枯水流量随着耕地面积的增大而减小.

Based on the monthly runoff data from Qin＇ an,Shetang,Tianshui,Wushan and Beidao Hydrology Stations of the main stream or main branches（ Huluhe River,Niutouhe River and Xihe River） of the Weihe River for 50 years from 1956 to 2005,features of annual minimum lowflowrunoff,monthly minimum lowflowrunoff and duration of lowfloware analyzed by using traditional probability statistics and time series analysis methods. Furthermore,formation mechanisms of lowflowrunoff and its extreme value are analyzed from two aspects as meteorology and human activity. The research indicates that annual mean runoff is many times larger than annual mean minimum runoff. The more complicated the underlying surface and the more frequent the human activities,the more percussive the minimum runoff. The minimum monthly mean runoff is more stable than the instant minimum runoff. Agricultural area shows a negative correlation with lowflowrunoff.