Study On Rule Of Contaminant Releasing From Sediment In River Network Area And Its Application In Coupled Model

Rivers in plan river network areas have some characters: velocity of flow is slow, water quality becomes worse, and sedimentation is serious. The contaminant from sediment releasing into water could cause "the second pollution". After consulting plenty of literatures about sediment releasing, the author found that there were complex factors can influence the sediment releasing. But some sediment model is too simple to incarnate the real condition of rivers, and others are too complex so that the parameters are difficult to ascertain. So the author choosed the biggish factor ofsediment releasing------hydrodynamic condition as the study object.This author usedstatic and dynamic experiments to simulate the sediment releasing rules in laboratory, which would be showed the rules of contaminant transference on the sediment-water surface in different hydrodynamic conditions.This paper choosed some representative river sediments in Taihu basin as the study objects of sediment releasing.And the targets of study included COD,NH₃-N,TN,PO₄^3-,TP. The author used used glass poles simulate sediment static releasing. The relusts of experiment showed the rule of exchange on sediment-water surface in static condition. Dynamic experiments using the taper bottles oscillation to simulate the sediment releasing in different hydrodynamic conditions, which achieved that the sedimenet releasing changed by velocity with exponential growth.The author coupled WASP5 water quality model with third-cascade river network hydrodynamic model to created hydraulics-water quality model in plan river network area. According to the configuration characters of WASP5 model, the author improved sediment releasing item, which adopted different forms in different current conditions. So this item can materialize movements at different time and space according to the experimental results. The author used the date of filed scale experiment in Zhang Jiagang area to calibrate the parameters of model. The result of improved model was better than other models. Finally this author used the model simulate water quality in 2002 in Zhang Jiagang river network area. The results achieved showed the coupling model can be used as a tool to simulate water environment in plain network area.