Study On Water Pollutants Total Amount Control Technique In Ashi River Basin Based On Non-point Source Pollution Control

Pollutants total amount control technique is an important means to reduce the basin’s pollutant total amount, improve river’s water quality and relieve the pressure of water environment. This study selected Ashi River Basin as the study area, explored the implementation method based on non-point source pollution control of small watershed pollutants total amount control technique. Through research and analysis of watershed characteristics,constructed the control unit of watershed water quality management, accounted the pollution load and water environmental capacity on a monthly basis, and established the pollution load distribution system based on non-point source poluution control. The main achievements of this paper are summarized as follows:(1) The control unit of water quality management in Ash River Basin was dividedAccording to the regional characteristics of the ash River Basin, Xiquanyan reservoir, Maanshan hydrometric station, Fuerjia Bridge and Ashi river estuary was selected as the control section and divided Ash River Basin into four control units. Guided by local policy, the water quality target of different units are determined, it changes from upstream to downstream as Ⅱ, Ⅲ, Ⅳ, Ⅴ respectively.(2) The pollution load of Ashi River Basin on a monthly basis based on non-point source pollution control was calculaedOn the basis of the control unit, maked non-point pollution as background values,the pollution load of the background, including industrial sources and urban life; and non-point source, including farmland non-point source, livestock farming and rural life was calculated. Results showed that the total amount of COD and NH3-N in the rivers were27467.14t and3318.95t respectively. Among them, the non-point source COD and NH3-N in the river quantity proportion were69.64%and70.56%respectively. The change from month to month of COD and NH3-N presented the bimodal trend, peaked in July, April second and minimum in January.(3) The water environment capacity of Ashi River Basin was estimatedOn the basis of one-dimensional river water quality model, outlet of the control unit was generalized, and response relationship between the control section and generalized water outlet was established. With proportional allocation as basic principle, the river water quality was simulated thourgh the weight coefficient model. Results showed that the water environment capacity of COD was11270.76t and NH3-N was496.05t.(4) The basin pollution load distribution system was establishedThe security margin of Ashi river basin was estimated and basin pollution load distribution system was established. With the control unit4as a case, the environmental capacity that can be allocated to background pollution, farmland non-point source, livestock farming and rural life was distributed.Ultimately the non-point source pollution load was distributed to dministrative units, and then determinated its reductions.