基于分布式水沙模型的大夏河流域水沙过程演变机理

Evolution Mechanism of Water and Sediment Processes in Daxia River Basin Based on Distributed Water and Sediment Model

黄河上游水沙过程受气候和土地利用变化等因素影响,年际及年内分布差异较大。选择大夏河流域为研究区,对研究区的实测径流和输沙量进行趋势性分析,应用流域分布式水沙模型(WEP-SED)模拟流域水沙过程并采用多因子归因分析方法进行分析,探究大夏河流域在变化环境下的水沙演变规律。结果表明:大夏河流域年径流量下降速率为0.85亿m 3/10 a,年输沙量下降速率为66.25万t/10 a,趋势均为负持续性,输沙量的减小幅度是径流量的1.8倍;大夏河流域水沙过程主要受汛期降水、气温以及土地利用变化的影响,降水对径流量和输沙量减少的贡献率分别为-77.0%和-90.0%,气温对两者的贡献率分别为-29.7%和-16.5%,而土地利用变化对两者的影响呈现微增作用。

The water-sediment process in the upper reaches of the Yellow River is affected by factors such as climate and land use changes,and its distribution varies greatly between and within the year.The Daxia River Basin was selected as the study area to analyze the measured runoff and sediment transport data.The watershed distributed water and sediment model(WEP-SED model)was used to simulate the water and sediment processes,and the multi-factor attribution analysis method was used to analyze the water and sediment evolution patterns of the Daxia River Basin under changing environments.The results show that the annual runoff decline rate of the Daxia River Basin is 85 million m 3/decade,and the annual sediment discharge decline rate is 662500 t/decade;the trends are all negative and persistent;the reduction in sediment volume is 1.8 times that of runoff;the water and sediment processes in the Daxia River Basin are mainly affected by precipitation,temperature and land use changes during the flood season;the contribution rate of precipitation to the reduction of runoff and sediment is-77.0%and-90.0%,and the contribution rate of temperature is-29.7%and-16.5%,respectively,while the impact of land use change on runoff and sediment increases slightly.