基于SWAT模型的乌鲁木齐河流域径流模拟

Hydrological modeling in the Urumqi River basin based on SWAT

为了更好地研究西北干旱区高山河流对气候变化的响应,在新疆乌鲁木齐河上游汇水区构建SWAT分布式水文模型,结合Sufi-2算法对模型进行参数率定、敏感性分析以及不确定性分析,对乌鲁木齐河英雄桥水文站以上2000-2011年日径流进行模拟。结果表明:(1)河岸调蓄的基流α因子、土壤饱和导水率、地下水的时间延迟、气温降水垂直变率以及相关融雪参数比较敏感。(2)模型模拟结果与观测流量过程线拟合程度较好,日值模拟结果 Ens>0.75,PBIAS介于±25%,R2达到0.8以上。(3)较高的P-factor及较低的R-factor显示模型不确定性较小。总体来说,SWAT模型在乌鲁木齐河上游区的适用性比较理想。

Water resources system is very fragile and the climate change in arid region is sensitive to the global climate,so it is necessary to enhance the water resources system in arid region of northwest to address climate change and allocate limited water resources rationally. It is absolutely significant to quantify the water resource in inland river basins especially in the arid zone of northwest China. This paper took the mountainous watershed of Urumqi River as a study area to simulate the hydrological processes of mountainous watershed in inland river basins by using soil and water assessment tool（SWAT）and sequential uncertainty fitting（ver.2）algorithm,and selected 25 parameters that were closely associated with the hydrologic processes to execute parameter sensitivity analysis. The sensitivity analysis results showed that ALPHA_BNK,SOL_K,GW_DELAY,TLAPS,PLAPS and some snow melt parameters（SMFMX,SFTMP,SMTMP）played a very important role in hydrological processes in the mountainous watershed and it is crucial to add elevation bands when the SWAT model was used in the mountainous watershed. SWAT daily simulation results showed that both the Nash-Sutcliffe efficiency and the determination coefficient values of the calibration period（2002-2006）and validation period（2007-2011）were higher than 0.75（monthly simulation results surpassed 0.85）,and the percent bias was controlled within ±25%,which indicated that the simulation results were satisfactory. In uncertainty analysis,the higher P-factor and lower R-factor also showed that the model uncertainty was relatively small. All these statistics make sure that it is feasible to use SWAT as a flow simulator in the upper reaches of Urumqi River. Also it could provide reference for other similar researches in the mountainous watershed of northwest China and support the further research in this river basin.