Study On Water Environment Carrying Capacity Based On SWAT In Yiluo River Basin

The Yiluo River Basin is an important part of the Yellow River Basin,The water management policies in the new era and the Yellow River Basin environmental protection and high-quality development strategies all emphasize the importance of ecological protection in the river basin.Water environment research at the basin level,non-point source pollution is a factor that cannot be ignored,Non-point source pollution is often overlooked due to its complex mechanism,uncertainty,and randomness,resulting in unsatisfactory evaluation and prediction effects of the water environment carrying capacity of the basin.Therefore,based on the concept of ecological protection and Xingfu River,it is necessary to introduce a hydrological model that can reflect non-point source pollution to study the water environment carrying capacity of the basin.Based on the analysis of the status quo of the water environment and the connotation of the carrying capacity of the Yiluo River Basin,an evaluation index system for the water environment carrying capacity of the basin based on the criteria of social economy,water resources,water pollution,and ecological environment has been constructed.Based on the AHP and entropy method,the TOPSIS method was revised,and the water environment carrying capacity evaluation model of the Yiluo River Basin was constructed.Use the SWAT software of the Arc GIS platform to perform numerical simulation of the water environment of the Yiluo River Basin,and calculate the water environment carrying capacity of the Yiluo River Basin from 2009 to 2018.And predict the water environment carrying capacity of the basin under different scenarios.The research results show that the overall change trend of the water environmental carrying capacity index of the Yiluo River Basin in the past ten years has been increasing.In 2012,the carrying capacity index was 0.424,which was out of a poor state,and reached 0.4714 in 18 years,which is close to the qualified state;By analyzing the change trend and contribution degree of the subsystems,the contribution of the socio-economic and ecological environment subsystems to the water environment carrying capacity of the basin is steadily improved.The water resources subsystem that has the greatest impact on the water environment carrying capacity of the Yiluo River Basin is the Yiluo River.The water environment carrying capacity of the river basin has been reduced in 2013 and 2014.The state of no carrying capacity is directly related to the decline of the water resources subsystem;Select 2014 and 2018 as typical years for analysis,use SWAT to divide the Yiluo River Basin into 25 sub-basins,analyze and calculate the carrying capacity of each sub-basin in 2014 and 2018,and the overall carrying capacity in 2014 is in a poor state.The above shows that the water environment carrying capacity in the southwest region is better than other sub-basin areas,and the overall deviation in the northern region.In 2018,the overall water environment carrying capacity was in a poor state.Compared with 2014,the overall improvement was large,and the carrying capacity in some areas even reached excellent,In good condition,the temporal and spatial distribution is similar to 2014;Based on the "13th Five-Year Plan" of Luoyang City and the CFSR World Weather Database,the water environment carrying capacity of the basin under different scenarios is simulated and predicted.The scores of the water environment carrying capacity under each scenario have been improved,of which scenario 4 has the largest increase,by 2020 The year has reached 0.5668,an increase of 20.24%.Scenario 2 has the smallest increase in the four scenarios,at 3.20%.