Study On Characteristics Of Water Pollution In Qingyi River Basin Based On SWAT

Accurate pollution control is one of the important policies to achieve the goal of pollution control in China,in addiction,it’s the basic and essential prerequisite for the realization of water pollution control to conduct research in order to clear temporal and spatial distribution and its type characteristics of water pollution in river basin.Qingyi river basin as one of the two main polluted rivers of Huaihe river basin Shaying river system,at the same time,as an important water body of flood control,drainage,sewage pollution and urban landscape water along the river area,the study on the characteristics of water pollution in this river basin is of great significance to the improvement of water quality in the basin and the water pollution control in the Shaying river basin and the water pollution control in the Huaihe river basin.Qingyi river basin is taken as the study area in this paper,appropriate water quality simulation index is selected based on the analysis of the status of the basin water environment,combined with the principle of SWAT water quality model.And then calibrate and rate the model parameters used the actual data of the basin runoff and water quality.Afterward,according to the SWAT simulation results and use the scenario setting method and separation judgment method to determine the characteristics of the basin water pollution,include the distribution of its spatial 、 temporal and the contribution rate of watershed point source and non-point source pollution,in order to provide the basis for the river basin water pollution control.The main contents and conclusion are as follows:Firstly,this paper analyzes the current of the basin water environment from two aspects: water quality evaluation and efficiency evaluation of sewage treatment plants.Among them,the former assessment can be used as a direct indicator of the water quality of the basin,the latter can be used as an important factor to reflect the water pollution control in this area.The result of water quality evaluation shows that the basin water pollution is more serious: the single factor evaluation indicates that the watershed is inferior V class,the beyond standard factors are COD、ammonia nitrogen and BOD;the single factor index method indicates that the ammonia nitrogen pollution is the most serious;the fuzzy comprehensive evaluation method shows that there are differences in the monitoring sections of the river basin,and the water quality of the same monitoring section is different in each month of a year.The export water quality of sewage treatment plants in the basin meet the class A standard of the “urban sewage treatment plant discharge standards”,both COD and ammonia nitrogen,however,there is still a certain gap compared with the surface class IV and V.Data envelopment analysis(DEA)is employed to establish an evaluation model of these sewage treatment plants,the results shows that half of the eight plants reach their relative optimal efficiency,there is no serious redundancy in the investment situation,only individual need to adjust the industrial structure and regulate the resources reasonably for those of which the efficiency is low.Ammonia nitrogen is selected as the simulation index,based on the analysis of water environment combined with the principle of SWAT,which provides the basis of the data collection,including the spatial and attribute database.Then,swat-cup is employed to calibrate and rate the model parameters,runoff and ammonia as the target variables respectively,and the calibration results are in accordance with the accuracy requirement,the model is suitable for the watershed,namely,SWAT can be used to simulate ammonia nitrogen pollution in the Qingyi river basin.Identify the characteristics of ammonia nitrogen pollution,including the main time,main area and the main type of the pollution source,according to the simulation results,in order to provide the evidence for the accurate management of water pollution.First of all,identify the time and spatial characteristics in accordance with the simulation results,and then identify the main source type,that is the contribution rate of the point and non-point source pollution by scenario analysis and separation evaluation method.The results show that the higher production of ammonia nitrogen is from May to September in terms of time,which is consistent with the trend of rainfall distribution.From the perspective of space,ammonia nitrogen yield is mainly influenced by human factors,and the area with higher ammonia nitrogen yield is located in change-xuchang section,which is consistent with the distribution of industrial cluster in the basin.In the terms of the pollution source,the non-point pollution is higher than the point pollution,the contribution rate is 53% and 47% respectively.