Runoff Simulation Of The Upper Reaches Of The Hanjiang River And Future Climate Change Response

Climate change is a hot issue of global concern,and water resource reform restricts the development of national economy and society.At present,the occurrence of extreme weather events,drought and flood,water environment deterioration and water pollution have seriously obstructed the sustainable development of society.It's of great significance to assess the water resources change in the future climate change and to the water resources management planning and sustainable utilization.In this paper,the study area for Hanjiang upstream basin,which is the water source of south-to-north water transfer project,the water resources allocation in north ordos project for water,significant livelihood of the people as a whole project.It is of great significance to study the change of water resources in the basin in the future.Research advances of this field were reviewed in this paper.On the basis of distributed hydrological model SWAT,Hanjiang river upstream watershed hydrological cycle system is simulated,using SDSM statistical downscaling model to predict the future meteorological elements under different scenarios.By coupling model of two scenarios for the future of runoff forecasting,the following conclusions are obtained:(1)The SWAT model has good applicability in the upper reaches of the Hanjiang river.The sensitivity parameters of runoff on the upper reaches of the Hanjiang river were identified as CH_N2,SOL_BD and SOL_AWC.In the model,the average monthly runoff simulation results,the relative error Re are all controlled under 10%,the determining factor R~2 and the Nash efficiency coefficient Ens are more than 0.8,and the evaluation level is B,etc.(2)The SDSM model suitable for this basin is constructed,and the atmospheric circulation factors of RCP2.6 and RCP8.5 are output in the CanESM2 model,the downscaling prediction is carried out in the SDSM model.The results showed that the rainfall is significantly increased compared with the base period,and the growth rate was 9.9~26.1mm per decade.The highest temperature rise will be slightly higher,every ten years is only 0.052~0.144?;The lowest temperature will be slightly is decreasing,every ten years is 0.018~0.082?.There was also a significant difference in the growth rate of different emission scenarios.RCP8.5 is significantly drastic than RCP2.6.(3)The CanESM2 mode output is coupled with the calibrated SWAT model to obtain the future runoff under the change scenario.The predicted results show that the runoff in the upper reaches of the Hanjiang river will fluctuate more than the benchmarking period in the future,and the runoff will increase,and the maximum growth rate can increase by 50m/s every per decade.In the scenario of RCP2.6,the runoff in February of 2020S and 2050S is very unstable,and the probability of drought or flood events increased,and the runoff is stable after the increase of 2020S.In the scenario of RCP8.5,there is a significant increase in the amount of runoff.