Study On Hydrological Model Of Basin And Runoff Response Under Climate Change

With society and economy developing,population of world growing and global climate changing frequently,the issues of water has been increasing serious,which has been also a bottleneck restricting the sustainable development of society and economy in the world,especially in China.The Pearl River is the second largest river in China.The Pearl River Basin is vast in area,complex and diverse in topography,geology,and vegetation.The Pearl River Delta region is the core of China's economy,with a large population density and low ability to withstand extreme climatic events,which make it more vulnerable to major socioeconomic losses causing by extreme climatic events.It is of great significance for the rational allocation and sustainable development of water resources in the Pearl River Basin to simulate the hydrological process scientifically,predict the future climate trend and water resources in the middle and upper reaches of the Pearl River Basin.Thus,taking the Lijiang River basin as the research object,this paper researches the karst-Xinanjiang model around the hydrologic process simulation of karst area.And taking the middle and upper reaches of Pearl River as the research object,this paper introduces VIC-3L distributed hydrological model,SDSM statistical downscale and CanESM2 climate model to study the future climate prediction and hydrological response under the changing environment.The following conclusions are drawn:In order to improve the accuracy of hydrological process simulation and prediction in karst area,a karst-Xinanjiang hydrologic model suitable for karst area is set up and applied to Lijiang River basin.The karst-Xinanjiang model is compared with the traditional Xinanjiang model from the simulation results of each water source and the backwater process.The results show that the simulation results of the karst-Xinanjiang model are more consistent with the hydrological characteristics of the karst region.The VIC-3L distributed hydrological model is applied to the upper reaches of the Pearl River,and the model parameters are calibrated by the coordinate rotation method,the simulation results are evaluated on the daily scale and the monthly scale with a variety of evaluation indexes.The results of all indexes show that the VIC-3L hydrological model can be applied to the runoff simulation of the study area,which can be used to study the water resource response of the region in the future climate change.SDSM statistical model and CanESM2 climate model are used to predict the future rainfall and temperature in the middle and upper reaches of Pearl River basin under three climate scenarios,and the built-up VIC-3L model is applied to predict the future runoff in the study area.The results show that the future rainfall is fluctuating and stable in all three scenarios,the interannual rainfall is between-24% and 29% of the base year,and the probability of extreme rainfall events will increase in the future.The total amount of longterm rainfall increased slightly relative to the base period under each scenario.The maximum temperature and the minimum temperature showed a stable trend under the RCP 2.6 scenario,while the temperature in the RCP4.5,RCP8.5 scenarios showed an obvious upward trend.And the minimum temperature value of the summer and spring will show an upward trend,autumn and winter are opposite.The runoff in each climate scenario is reduced relative to the base period.And it shows a fluctuating and stable trend in each scenario,and the peak of discharge in the middle and later period of the 21 st century will be transferred to June.The probability of flooding this month will be greatly increased and the volume of discharge in July-August will be reduced in the late 21 st century.