Study On Runoff Response Under Global Change Scenarios

Water is one of the most important resources in the world,which need our protection.It is very important to study the effects of climate,land use and soil change on water resources to protect the safety of using water.This paper,using the SWAT model to simulate the runoff of Jinqian River,the applicability of the SWAT model in Jinqian River Basin was achieved,and on this basis,combining the a variety of scenarios design to analyse the response characteristics of runoff under different scenarios.The main conclusions of this study were as follows:(1)The sensitivity analysis was carried out by SWAT-CUP,and the 15 parameters which had great influence on the simulation results were found through a large number of iterative operations: CANMX,CN2,SOL_K,ESCO and so on.Based on SWAT model the Monthly Scale simulation of Jinqian River Basin runoff was finished,which in the calibration period(from 1998 to 2002)the value of Ens was 0.73,R2 was 0.76 and Re was-15.7%,and in the validation period(from 2003 to 2007)the value of Ens was 0.75,R2 was 0.78 and Re was-18.1%,the simulation result was good.(2)Analyzing the scenario simulation of land use data and time climate data,obtained the conclusion that from 1998 to 2012 the impact of climate change on Jinqian River runoff is much higher than the impact of land use change,analysis of its reason and discover the change rate of land utilization area in drainage basin is less than 1%,and the change rate of rainfall which directly effect the runoff was 11%.By simulating basin runoff under different climate changes,we found that the runoff of Jinqian River was positively correlated with precipitation,but negatively correlated with temperature,at the same time that the response degree of Jinqian River runoff to rainfall change is higher than the response degree to temperature change,and the runoff rate of Jinqian river caused by precipitation change of 10%,20% is respectively 6.4 times,9 times higher than the change caused by temperature change of 1? and 2?.(3)By setting the extreme situations,we found that the increase of agricultural area wound increase the runoff,and the increase of forest area wound decreased the runoff,and the influence degree of forest to the runoff of Jinqian River is-48.83%,while the influence degree of agricultural land is 14.19%,which suggested that in Jinqian River basin the effect of forest on runoff is higher than that of agricultural land.We also found that the mainly 4 kinds of Soil in Jinqian River basin,CMe2(Eutric Cambisols 2)influence the runoff greatest that its impact is 8.3%,and the influence sequence of other remaining 3 kinds of soil is CMd(Dystric Cambisols)>CMe1(Eutric Cambisols 1)>LVh3(Haplic Luvisols 3),of which the influence degree of CMd is-2.8%,CMe1 is-1.2%,LVh3 is-0.7%.