Study On The Effects Of Rainfall-Runoff On The Water Quality In The Haihe Mainstream In Tianjin

Haihe River is the mother river of Tianjin,playing an important role in draining flood,shipping,landscape,and so on.But pollutant concentrations are usually over the ? water quality standard,and the water quality is even worse,especially in the flood season.Therefore,water pollution control must be carried.One of factors resulting in water pollution is rainfall-runoff.The purpose of this study is how to improve the water quality in Haihe River in the flood season.In order to obtain the volume of runoff and pollution load,the SWMM model was built;In order to simulate the water quality in Haihe River,the one-dimensional hydrodynamic and water quality model was built based on MIKE 11.The main contents and achievements are as follows:(1)P-? curve was used to obtain 24 h rainstorm with a return period of 1,2,3 and 5 years.And the rainstorm process was obtained based on Tianjin rainstorm atlas.Then the volume of runoff and pollutants was got by SWMM model.(2)The one-dimensional hydrodynamic and water quality model was built by MIKE11,and the output of SWMM was input into the model as lateral inflow.The average pollutant concentration was used as the index to show water-quality variation.(3)Three measures were used to improve the water quality,and the one-dimensional hydrodynamic and water quality model was used to simulate the effect of different measures.In a word,the effect of sewage treatment plants was limited.The effect of Duliujian River Wetland on TN and TP was better than COD.The effect of water diversion on water quality was greater when the return period was shorter.