基于数字滤波法的长江上游流域基流时空分布特征

Spatiotemporal Variation Characteristics of Baseflow in the Upper Yangtze River Based on Digital Filter Method

基流是枯水期河川径流的重要补给来源。精确刻画长江上游流域基流的时空分布特征,对水资源合理的开发和利用有着重要的意义。将数字滤波法和SWAT模型相结合,开展了长江上游流域基流在时间特征上的研究,并利用克里金插值方法实现了长江上游流域基流空间分布的刻画。结果表明:1990—2000年长江上游流域多年年均基流量和多年年均基流模数的范围分别为:5~9500 m^(3)/s和0.36~28.00 L/(km^(2)·s);年径流量、年基流量与年降水量均呈现出明显的正相关关系,而年基流指数与年降水量呈现出明显的负相关;基流指数(BFI)在年际变化上较为稳定,表明基流是河流的重要补给来源。基流指数在年内变化存在枯水期>丰水期的关系,基流量在年内变化规律为夏季>秋季>冬季>春季、丰水期>枯水期;此外,长江上游流域基流量随着产汇流面积的增加而逐渐增加。

Accurately depicting the spatial and temporal distribution characteristics of base flow in the upper Yangtze River is crucial for the rational development and utilization of water resources,particularly as it serves as a significant recharge source for river runoff during dry season.To achieve this,we combined the digital filtering method and the distributed hydrological model SWAT to analyze the time characteristics of base flow.Additionally,we employed a spatial interpolation method to describe the spatial distribution of base flow in the upper Yangtze River.The results demonstrate that the value and modulus of average annual base flow in the upper Yangtze River ranged from 5 to 9500 m^(3)/s and 0.36 to 28.00 L/(km^(2)·s)during the period from 1990 to 2000.Furthermore,we found a clear positive correlation of annual runoff and base flow with annual precipitation,whereas the base flow index(BFI)shows a distinct negative correlation with annual precipitation.The BFI exhibits relatively stable inter-annual variation,with a variation within the year showing a higher base flow during the dry season compared to the wet season.This indicates the crucial role of base flow in supplying rivers.In terms of seasonal variation,summer sees the largest base flow,followed by autumn,winter,and spring in sequential order,reflecting that base flow in wet season is larger than that in dry season.Moreover,the base flow in the upper Yangtze River basin increases progressively with an increase in runoff generation and concentration area.