Impact Analysis on Water Quality of the Second Songhua River Based on Mathematical Model

Water quality of the second Songhua River is affected by both tributary pollution loads and upper boundary.A set of hydrodynamics and water quality coupling model of the second Songhua River was developed.Based on the model, the pollution contribution ratios of tributaries pollution loads and boundaries were ascertained.The impacts of the change of water qualities of upper boundary and tributary were analyzed, and the farthermost water quality improvement of second Songhua River when upper boundary being better and tributary meeting Class III of National Surface Water Quality Standard was predicted.The results indicated: 1)if the tributary (Yinma river )meets Class III of National Surface Water Quality Standard, the water quality of WUJIA water quality monitoring station in Songhua river improving will be bigger from Jun through Aug, Ammonia and Nitrogen Index was significantly improved, but to upper boundary, this kind of impact is bigger.2) Both reducing the tributaries pollution loads and improving upper boundaries are necessary for improving water quality in the second Songhua River.