The Water Quality Improvement through Two Pollutant Load Allocation Methods in Gehu Lake, China

Due to many industrial and domestic pollution sources gathered around Gehu Lake and the lack of effective reduction measures, the ammonia nitrogen and total phosphorus in a large area of the lake exceed the standard. In order to control the amount of pollutants flowing into the lake, this paper selects two allocation methods to determine the load allocation of ammonia nitrogen and total phosphorus under the constraint of environmental capacity. The environmental fluid dynamics code model is used to verify the validity of the load allocation scenarios. The results showed that the concentrations of ammonia nitrogen and total phosphorus in Gehu Lake were lower by equal proportional allocation than by the contribution ratio allocation method. For ammonia nitrogen, the area exceeding the water quality standard is reduced more by the equal proportional allocation method (up to 100%). While for total phosphorus, the area exceeding the water quality standard is reduced more according to the contribution ratio allocation method (up to 96.3%). Considering that the two pollutants should be reduced simultaneously as much as possible, the equal proportional allocation method can be selected.