变化环境下渭河流域径流丰枯遭遇变化特征及其影响因素分析

Synchronous asynchronous encounter probability of rich-poor runoff change and its influencing factors under the condition of changing environment in the Weihe River Basin

以渭河流域为研究对象,采用有序聚类与滑动t检验法诊断渭河干流(咸阳站)、泾河(张家山站)与北洛河(状头站)1960-2010年径流变异情况,引入Copula函数分析不同水文区径流丰枯遭遇特征。结果表明:咸阳站径流于1969年、1993年变异,张家山站于1996年变异,状头站于1994年变异;变异点前后,各水文区相同设计频率下径流量显著减小,干流减小趋势最为显著;不同水文区径流丰枯遭遇概率变化显著,1960—1993年径流丰枯同步遭遇概率远大于丰枯异步,1994—2010年,除张家山-状头径流遭遇组合外,径流丰枯同步遭遇概率远小于丰枯异步,不同组合遭遇概率趋向均匀化;流域内不利于调水概率显著减小,持续且剧烈的人类活动对径流的改变是造成该现象的主因。

Taking Weihe River Basin as the study area, ordered clustering and sliding t methods .are used to detect the change point of runoff at the Xianyang station located in the mainstream of Weihe River, Zhangjiashan station located in the Jinghe River and Zhuangtou station located in the Beiluohe River. And Copula function is applied to analyze the synchronous-asynchronous en- counter probability of rich-poor runoff. Results show： the change point of runoff occurred in 1969 and 1993 at the Xianyang station, 1996 at the Zhangjiashan station and 1994 at the Zhuangtou station. In comparison of runoff at different design frequencies from 1960 to 1993, runoff decreased remarkably at the corresponding design frequencies from 1994 to 2010, which was most significant in the mainstream of Weihe River. The synchronous asynchronous encounter probabilities changed remarkably in all hydrological zones. From 1960 to 1993, the synchronous encounter probabilities were greater than asynchronous encounter probabilities, which was inverse from 1994 to 2010 except the Zhangjiashan-Zhuangtou runoff encounter combinations. Additionally, the range of synchronous asynchronous encounter probabilities of different rich-poor runoff combinations decreased from 1994 to 2010, and the frequency against water diversion also decreased greatly. Sustained and intensive human activities changing runoff were the main reason for cau- sing the changes of synchronous asynchronous encounter probability of rich-poor runoff.