Simulation Study Based On WASP And The Managenmt Study Of TMDL For The Daye Lake

According to the “China Environmental Bulletin 2016”,the compliance rate of the assessment section for key river in China is 75.4%,and 13.4% out of 112 key lakes are inferior V,indicating that the water environment in China is not optimistic and lake pollution situation is serious,so deepening the prevention and control of pollution in key river basins has become one of the focuses of China's Water Pollution Prevention Action Plan.Huangshi has a large number of rivers and lakes,with abundant water resources.In recent years,with the rapid development of social economy,it has left a huge "ecological deficit",and water environmental problems have also become increasingly prominent,mainly in terms of deterioration of water quality.In May 2012,the Hubei Provincial People's Congress passed the Regulations of the Hubei Province on the Management of Lakes.Daye Lake was included in the first batch of lake protection lists and ranked first in Huangshi City.The pollution of Daye Lake's water environment has restricted Huangshi's socio-economic development and cannot meet the needs of citizen life.Therefore,it is imminent to strengthen the prevention and control of water pollution in Daye Lake.This paper establishes the TMDL program for the Daye Lake basin,and explores practical pollution load distribution methods based on the actual situation,proposing pollution control strategies in the river basin to accumulate experiences for other lake management method systems in China.This paper takes Daye Lake as the research object,analyzing the characteristics of natural resources,social economy,and hydrology of the Daye Lake drainage basin.Based on the evaluation of the water quality of Daye Lake's regular monitoring sections over the years,the water quality survey is carried out and Kriging Interpolation method was used to study the temporal and spatial variability of water quality in Daye Lake.The output coefficient method was used to calculate various pollution source loads in the Daye Lake Basin.A WASP model was constructed to simulate the water quality changes in Daye Lake,and the applicability of the model was verified.Subsequently,using the model trial-and-error method,the Daye Lake's pollution capacity and daily maximum pollution load were explored,and TMDL was assigned to various types of pollution sources by the same ratio method.Finally,we forecast the discharge status of various pollution sources in the Daye Lake Basin in 2020,combine the allowable load,and determine the reduction amount of each pollution source to propose the Daye Lake TMDL program control measures.The main findings are as follows:(1)The water quality of Daye Lake in recent years is maintained at Grade IV of the "Surface Water Environment Quality Standard"(GB3838-2002),and the spatial distribution of total nitrogen and total phosphorus shows obvious variation characteristics.Although water quality has improved in recent years,it still fails Grade III standards.The pollution is mainly concentrated between Dagang estuary and Daye Bridge.(2)According to the pollution load of the river basin,the total nitrogen and total phosphorus intake in Daye Lake are: 1673.02t/a and 152.75t/a respectively.The non-point source is the major source of pollution in Daye Lake,among which agricultural planting and rural life are particularly prominent.(3)The maximum daily pollution load of total nitrogen in Daye Lake is 2827kg/d,and the maximum pollution load of daily total phosphorus is 142kg/d.According to the prediction of the pollution load of the Daye Lake Basin in 2020,the total nitrogen load of point source and non-point source was reduced by 314.2kg/d and 1210.5kg/d,respectively,and the total phosphorus was reduced by 25.59kg/d and 224.41kg/d,respectively.(4)Based on the actual conditions of Daye Lake,combined with the TMDL plan,the maximum daily total pollution control starts with four aspects of technical measures,management measures,economic measures,and public participation to provides theoretical guidance for pollution control of Daye Lake.