Study On The Impact Of Climate Change On Water Quality In Yuqiao Reservoir Based On Model Simulation

Research on the impact of climate change on water environment has been a hot issue.Due to the accelerated urbanization and rapid economic development,it has brought more risks and uncertainties to water resources management.At the present stage,the research on the impact of climate change on water environment mainly focuses on the impact on watershed runoff under climate change,and does not deeply study the impact of climate change on water quality in water environment.In such a context,this paper proposes a model simulation-based research scheme on the impact of climate change on water quality in the aquatic environment.The program constructs a water quality model;couples the global climate model in the International Model Comparison Program,and predicts the characteristics of climate change in the study area through the statistical downscaling method;couples the climate change model with the water quality model with the help of MATLAB software.And the scheme is validated by taking Yuqiao Reservoir in Tianjin as an example.Firstly,this paper introduces the theory of water quality model construction,model parameter estimation methods(Markov chain Monte Carlo(MCMC)algorithm and genetic algorithm(GA)method),climate change downscaling method and climate change and water quality model coupling method.The water quality model of Yuqiao Reservoir was constructed using the combined GA-MCMC method,and the parameters of the water quality model were rate-determined and calibrated.Secondly,we coupled the global climate model of the International Model Comparison Program(IMCP)to downscale the temperature and precipitation in the Yuqiao reservoir area and predict the future climate change characteristics of Yuqiao reservoir under two climate change scenarios,RCP4.5 and RCP8.5,by bias correction and spatial reduction(BCSD)downscaling methods.Finally,Boltzmznn temperature-water temperature statistical model was used as the connection point between climate change and reservoir water quality model to couple the future climate change characteristics with reservoir water quality model and analyze the impact of climate change on the water quality.The results of the study with Yuqiao reservoir as an example found that GAMCMC is an effective parameter calibration method and Yuqiao reservoir water quality model reproduces better.The global climate model has good applicability in the Yuqiao reservoir area.The Nash-Sutcliffe efficiency coefficients(ENS)of both temperature and precipitation are above 0.6,which better simulate the characteristics of climate change in Yuqiao reservoir.The prediction results show that the future temperature increases at 0.29°C/10 a and 0.69°C/10 a under RCP4.5 and RCP8.5 scenarios,respectively.The correlation analysis between climate change and water quality indicators based on Pearson correlation analysis showed that the correlation values between total nitrogen and total phosphorus and precipitation and temperature were high and positive,while dissolved oxygen and total phosphorus and total nitrogen were negatively correlated.Dissolved oxygen was negatively correlated with total phosphorus and total nitrogen,and dissolved oxygen was also negatively correlated with water temperature and air temperature,but the correlation values were not high;chlorophyll a was weakly correlated with water temperature.The method based on model simulation of climate change impact on water quality in the aquatic environment is useful and effective.In order to provide a decision basis for adapting to future climate change on the management of reservoir water environment.