Research On River Water Environment Capacity Based On ArcSWAT Model ——Taking The Liaohe River Basin In Liaoning Province As An Example

Due to the rapid development of industry and agriculture,a large amount of industrial waste water has entered rivers,resulting in river pollution has become the focus of attention.In order to understand the status of water pollution in Liaohe River basin,this paper selects liaohe River basin in Liaoning Province as the research area.SWAT model is used to simulate point source and non-point source pollution in the basin,and water environmental capacity is calculated based on one-dimensional water quality model.It is of great significance to solve the pollution problem of rivers and optimize water quality.The main research contents and achievements are as follows:（1）The basic database of SWAT model was built to simulate the distribution of point source pollution and non-point source pollution in liaohe River Basin,and the sensitivity analysis of parameters was performed as well as the calibration and validation of the model.The liaohe river in liaoning province is divided into 44,through the model calibration and parameter analysis,the hydrology,water quality monitoring station determination coefficient R~2were greater than 0.6,the NS values are positive,and determined the deviation is not big,the simulation results with measured results meet the requirement of hydrology and water quality simulation,and proved that the SWAT model is suitable for liaohe river basin of point source and non-point source simulation.Based on SWAT model simulation results confirmed the point source pollution and the spatial distribution of agricultural non-point source pollution situation,determine the research area of 19,24,33,38,40 song river basin of non-point source pollution is heavier,1,4,9,22 song river basin of non-point source pollution is heavier,clear the distribution of main pollutants in the study area,It provides basis for future water pollution control.（2）One-dimensional water quality model is selected to calculate water environmental capacity.According to the simulated amount of pollutants into the river by SWAT model,the monthly average flow data of 19 hydrological stations from 2009 to 2017,the monthly average water quality data of 25 water quality monitoring stations from 2010 to 2018,as well as the spatial distribution of COD,ammonia nitrogen,total nitrogen and total phosphorus in the main stream of Liaohe River,liaoning province was completed by using the end of segment control method.The final calculation results are as follows:COD water environmental capacity is89214.98 t/a,ammonia nitrogen water environmental capacity is 4856.12 t/a,TN water environmental capacity is 36712.96 t/a,TP water environmental capacity is 972.09 t/a.In dry season,the environmental capacity of COD water is 30861.77 t/a,ammonia nitrogen water is1679.86 t/a,TN water is 12699.96 t/a,TP water is 336.27 t/a.The environmental capacities of COD,ammonia,TN and TP in wet season are 206280.25 t/a,22122.52 t/a,110285.04 t/a and7864.92 t/a.In dry season,the environmental capacity of COD,ammonia,TN and TP is71357.69 t/a,7652.75 t/a,38150.45 t/a and 2720.68 t/a.