Runoff Simulation Based On SWAT Model In The Aksu River Basin,Xinjiang,China

The Aksu river basin,Xinjiang is located in the arid area of northwest China,its runoff is composed of melt water and precipitation.Due to the common influence of human activity and climate change,the phenomena on water shortage and deterioration of water environment are increasing serious.As the main recharge source of the Tarim basin,the runoff change of Aksu river plays a important role in the sustainable development of nature,ecology and social economy of the Aksu river and the whole Tarim basin.Therefore,developing an accurate distributed hydrological model,studying the hydrological process and analyzing the effect of climate change on runoff quantitivly provide scientific basis and theoretical foundation for ensuring the rational allocation and utilization efficiency of water resources.The distributed hydrological model-SWAT was selected to simulate the runoff in Aksu river basin.The main contents and results of this paper are as follows:1.By using DEM,landuse data,soil resources and climate date from 1980 to 2013,spatial and attribute databases were established which SWAT model needed.Based on DEM of Aksu river basin,the channel was extracted based on the hydrological analysis module and the study basin was divided into 18 sub-basins and 201 hydrological response units on the basis of underlying surface information,including landuse data,soil resources and slope classification.Terrain,snow storage and snow melt parameters were determined,and the sensitivity and uncertainty of all parameters were analyzed.2.According to the SWAT-CUP module,measured monthly runoff data of Alar hydrologic station from 2000-2006 and 2007-2013 were used to calibrate and validate the model.The results showed that in the calibration and validation period,relative error R_E was-4.75%and-7.98%,relative coefficient R~2 was 0.89 and 0.84,Nash-Sutcliffe efficiency coefficient NSE was 0.89 and 0.82.Although the simulation results were less than measured values both in calibration and validation period,the comparatively accurate changing trend of practical runoff was reflected on the whole.Each of the evaluation indexes had reached the requirement of SWAT and got a high simulation precision,which showed that the SWAT model was applicable for Aksu river basin.3.Based on the climate data of seven weather stations of the Aksu river from 1980to 2013,25 kinds of hypothesis climate change scenarios were established and the effect of climate change to the runoff of basin was analyzed.The results indicated that climate change had a significant effect on runoff.There was a positive correlation between runoff and precipitation,and a negative correlation between runoff and temperature.Compared to temperature,runoff was more sensitive to precipitation.The effect of precipitation to runoff was decreased when the temperature rised,and temperature to runoff was increased as the increasing of precipitation.Under different kinds of climate change scenarios,runoff change had a significant difference.