Hydrological Modelling Of Buy-Uanjiang River Basin Using MIKE SHE

Since the last century,high-intensity human activities and climate change have influenced the water cycle.The hydrological changes in the basin caused by climate and land use changes are gradually receiving attention from the public,which prompted researchers to accelerate the process of quantitative research in hydrology.As a quantitative research tool for hydrology,the MIKE SHE hydrological model has been rapidly developed with wide application in numerous regions and fields.However,the current study does not involve the application of the Longitudinal Ridge Gorge Region(LRGR).LRGR is located in the southwest of China,which is the upstream of many international rivers.The issues concerning hydrological and water resources in this area are sensitive and complex,and their cross-border effects are of great concern to the international community.In addition,river runoff changes will exert a comprehensive impact on the water environment and aquatic ecosystems in the basin.In addition,the simulation of river runoff is conducive to the rational allocation of water resources in the basin as well as the protection of aquatic ecosystems.In this paper,the MIKE SHE hydrological model is used to carry out the runoff simulation study in the Buyuanjiang River Basin.Besides,the scenario analysis method is employed to analyze the runoff response of climate change and LUCC.The main conclusions are shown as follows:(1)Through the collection and processing of hydrological and meteorological data as well as geographic information in the Buyuanjiang River Basin,the database for running MIKE SHE model was successfully built.The runoff simulation of the basin was carried out through the methods of MIKE SHE and MIKE 11 model coupling operation.The simulation results show that the simulated flow graph and the measured flow graph are well matched.Besides,the Nash-Sutcliffe efficiency coefficient is 0.77 and the correlation coefficient is 0.88.indicating that the MIKE SHE hydrological model has better applicability in the LRGR.(2)Under the emission scenarios of RCP 4.5 and RCP 8.5,the average annual temperature in the Buyuanjiang River Basin is 21.52 "C and 21.67 0C in 2020?2049,and the annual average precipitation is 1783 mm and 1797 mm,respectively.The air temperature,rainfall and potential evapotranspiration of the RCP4.5 and RCP8.5 emission scenarios(2020?2049)will be higher than those of the historical period(1980?2005).It shows that under the RCP4.5 and RCP8.5 emission scenarios,the characteristics of warming and precipitation increase will occur in the Buyuanjiang River Basin.(3)Based on the CMIP5 global climate model,the climate change scenarios of the Buyuanjiang River were established,and the runoff processes under different scenarios of 2020?2049 were also simulated.The simulation results demonstrate that according to the climate change characteristics of the RPC4.5 and RCP8.5 scenario under the CMIP5 global climate model,the annual runoff of the Buyuanjiang River Basin will change to a certain extent.Compared with the Base period(1959?2012),The amount of change of the annual runoff phase in the climate change scenarios of RPC4.5 and RCP8.5 is-1.9%and-1.3%,respectively.However,the annual runoff will increase during the period from 2020 to 2049 under the two emission scenarios.From the perspective of the interannual variation of runoff,the interannual variation of runoff under the RCP4.5 emission scenario is closer to the interannual variation of runoff in the baseline period,and the interannual variation of runoff under the RCP8.5 emission scenario is more severe.In addition,the distribution characteristics of the climate change scenarios during the year are all more evenly distributed during the year than the current scenarios.(3)Based on the MIKE SHE hydrological model,the hydrological response of rubber plantations and tea gardens to forest land was explored by employing the method of extreme land use scenarios.The annual runoff of Buyuanjiang River will be reduced by 0.46%,if all rubber plantations are converted into forest land,and all annual runoff will be reduced by 0.55%when all tea gardens will be converted into forest land,indicating that if the area of the garden is reduced and the area of forest land is increased,it will,to a certain extent,reduce the runoff output of the basin.Different degrees of expansion in rubber plantations and tea gardens will increase runoff.However,the magnitude of the change is small.