Hydrological Simulation Of The Tail Section Of Ganjiang River Under Climate Change And Its Impact On Water Environment

It is of great significance to study the influence of climate change on the water environment of the tail section of Ganjiang River,which can provide certain scientific basis for the protection of the water environment of the tail section of Ganjiang River.In this paper,it is based on the regional climate model RegCM4.6,the future meteorological data of Ganjiang River Basin are predicted,and the SWAT model is used to simulate and predict the runoff data of Waizhou hydrologic station in the future period under three discharge scenarios of RCP2.6,RCP4.5 and RCP8.5.Then the MIKE two-dimensional hydrodynamic water quality model is used to simulate the ammonia nitrogen situation in the tail reach of Ganjiang River Basin under the three discharge scenarios,and the variation of ammonia nitrogen concentration in the tail section of Ganjiang River under the three discharge scenarios is analyzed by using the runoff data of the three discharge scenarios as the input data.The main conclusions of this paper are as follows:(1)the monthly and annual average,Interdecadal,spatial,trend and sudden change analysis of temperature,precipitation,wind speed,relative humidity,sunshine hours and runoff in Ganjiang River Basin are carried out for many years.The trend changes in the southeast,southwest and northwest of the basin are not significantly increased,the Interdecadal variation is obvious,there are abrupt years,the temperature distribution in the east-west direction of the basin is uneven,and the trend change is significantly increased.The Interdecadal variation first cooled and then warmed up,and there was a sudden change in the wind speed in the southeast and northwest,the trend decreased significantly,the Interdecadal variation continued to decrease,the relative humidity in the west and northwest of the basin was larger in the west and northwest,the Interdecadal variation was obvious,the trend was not significantly decreased,and the sunshine hours in the west and northwest of the basin increased to the south and southeast.The Interdecadal variation is obvious,the trend change is significantly decreased,there is a sudden change year,the annual variation of runoff is close to the rainfall,the distribution of runoff in the year is uneven,the difference is great,the trend change is not significantly increased,there is a sudden change year,precipitation has the greatest impact on runoff.(2)based on the global climate model MPI-ESM-MR data,the regional climate model RegCM4.6,of Ganjiang River Basin is constructed to compare and analyze the precipitation,temperature and maximum minimum temperature in the historical period.The results meet the error requirements,and then predict the future rainfall,air temperature and maximum minimum temperature under the three emission scenarios of RCP2.6,RCP4.5 and RCP8.5,and analyze their variation laws.In the next 70 years,the maximum and minimum temperature increases more obviously with the increase of typical concentration,but the precipitation does not decrease significantly in RCP2.6 scenario,but does not increase significantly in the other two emission scenarios.(3)the SWAT hydrological model of Ganjiang River Basin is constructed by using the relevant basic data of Ganjiang River Basin,and its applicability in Ganjiang River Basin is judged by the runoff data of Wazhou Hydrological Station.The results meet the evaluation criteria.It is proved that the SWAT model can be used to simulate the runoff of Ganjiang River Basin.With the increase of typical concentration,the trend of runoff is the process of increase.The average monthly runoff value of RCP2.6 emission scenario is the largest for many years.The three emission scenarios increase gradually from January to May and decrease gradually from May to December.(4)the hydrodynamic water quality model of the tail section of Ganjiang River is established,and the water quality data of Nanchang Water level Station and Chucha Hydrological Station are used to verify the water quality data.The results meet the error requirements.Under the simulated three discharge scenarios,the concentration of ammonia nitrogen changes in the future period.With the increase of typical concentration,the temperature rises obviously,and the increase of climate will accelerate the degradation of pollutants and reduce the pollution load of the river.Therefore,the water quality of RCP8.5 emission scenario is better than the other two emission scenarios.