Analysis Of Runoff Variation Characteristics And Its Driving Factors In Guishui River Basin Based On SWAT Model

It is of great importance to fully guarantee the sustainable utilization of water resources in the Guishui River Basin(GRB),which serves as a significant ecological barrier of Beijing and one of the three venues of 2022 Beijing Olympic Winter Games.However,the increasing climate change and human activities in recent decades have brought severe challenges to the management of water resources in the GRB.This study takes the GRB as the research object.Firstly,a SWAT model suitable for this basin was constructed and the runoff was simulated.Then,based on the analysis of the spatio-temporal evolution characteristics of runoff,the impact and contribution rate of climate change and human activities to runoff change in the GRB was quantitatively analyzed combined with the runoff impact assessment model.Mainly achieved the following research results:(1)The evaluation indexes in both the calibration and validation period meet the requirements of simulation accuracy,which indicates that this SWAT model has a good application in the GRB.(2)The annual runoff in the GRB from 2004 to 2018 is generally low,showing an increasing trend with different fluctuation during this period.In the seasonal scale,runoff shows a decreasing trend in spring and winter,while it shows an increasing trend in summer and autumn.On the spatial scale,the subbasins in the middle could produce greater runoff depth.The overall spatial distribution shows the characteristics of "increase first and then decrease" from northwest to southeast.(3)The climate change and human activities contributed 60% and-40% to the runoff change in the GRB.And the contribution of land use change including in the human activities to the runoff change of this basin accounts for-5%.Climate change could cause an increase in runoff,while human activities may lead the runoff to decay continuously.(4)When analyzing the impact of precipitation and temperature contained within climate factors on the runoff,it is found that the average precipitation in GRB from 2004 to 2018 presents an overall rising trend,and the climate gradually became wet.Meanwhile,the annual precipitation concentration degree is high,and the precipitation concentration period fluctuates in the middle of July.The increase of precipitation promoted the increase of runoff in the basin as a whole.In terms of temperature,it increased,which also promoted the increase of runoff from 2004 to 2018.In general,the climate of the GRB has a tendency to "warm and wet",which has promoted the increase of runoff.(5)The specific analysis of the impact of land use change included in human activities on runoff shows that: due to the positive influence of reservoir water replenishment after 2012,the negative impact of industrial,agricultural,living and ecological water consumption on runoff was partially offset during the baseline period,that is,the reduction contribution of human activities to runoff was gradually weakened,and runoff was developing towards a better state.(6)Based on the analysis of runoff evolution characteristics and its driving factors in the GRB,this study puts forward relevant suggestions from the three levels of total water resources control,recycling and coordinated management in order to promote the better management and utilization of water resources.