Influence Of Climate Change On Water Inflow And Total Phosphorus Load Based On Regional Climate Models In Yuqiao Reservoir Basin

Climate change has a more obvious change in the status of the hydrological cycle on a longer time scale,which will cause the redistribution of water resources in time and space.Yuqiao Reservoir is an important water source in Tianjin.The changes in water volume and water quality in the future for a long period of time are closely related to the life of Tianjin people.Therefore,it is helpful for the future utilization and comprehensive management to study the impact of future climate change on reservoir water inflow and total phosphorus load.In this paper,the numerical simulation method is used to quantitatively evaluate the impact of different climate change scenarios on the reservoir water inflow and total phosphorus load.Based on the downscaled meteorological data of multiple regional climate models(RCMs)in different climate change scenarios(RCP4.5 and RCP8.5),the Bayesian model averaging method(BMA)is used to weight the average integration of multi-model data,and the inverse distance weight interpolation method is used for the second downscaling.Then the data was used as the input of distributed hydrological model SWAT to predict the water inflow and total phosphorus load in the 2016-2030 period and 2031-2050 period under different climate change scenarios.Finally,the impact analysis was carried out.The main conclusions are as follows:(1)The resolution of meteorological data after BMA weighted average integration and secondary downscaling is increased from 0.5°×0.5° to 0.1°×0.1°,and the correlation coefficient between the second downscaling data and the observed data of each meteorological variable is above 0.9.The observed and simulated data were in good agreement.(2)During the calibration period(1996-2005).In runoff simulation,the coefficient of determination is above 0.5,the average efficiency coefficient is 0.88,the average relative deviation is-1.3%,the total phosphorus load simulation coefficient of determination is 0.61,the efficiency coefficient is 0.57,and the relative deviation is 19.2%.During the validation period(2006-2010),the simulated and observed data were close,and all meet the accuracy requirements.In general,the model has good applicability to the Yuqiao reservoir watershed.(3)Using the data containing multi-percentile flow to calibrate the SWAT parameters can reduce the simulation uncertainty.(4)With the increase of temperature and precipitation,the water inflows of different climate change scenarios have increased from the historical period,and the RCP8.5 scenario will have greater changes in runoff.Both scenarios will be redistributed during the year,and the flood season will lag.The sharp increase of precipitation in summer and autumn will also greatly increase the water inflow in autumn.In other seasons,due to the increase in temperature and little change in precipitation,evaporation will increase and water inflow will decrease.The total phosphorus load is mainly affected by the erosion and migration of agricultural non-point sources by rainfall and runoff.With the increase of precipitation,the storage load of RCP4.5 and RCP8.5 scenarios have increased relative to the historical period,with an increase in precipitation.In the larger RCP4.5 scenario,the increase in total phosphorus is also larger.The distribution of the two scenarios during the year is similar to runoff.