Study On Hydrodynamic And Water Quality Simulation Of Constructed Wetland

In recent years,the water quality of Yuqiao reservoir which is the important water supply source for Tianjin has deteriorated continuously.For this purpose,water source protection engineering that the constructed wetland is an important component will be constructed around Yuqiao reservoir,It is intended to be the upper reaches of the reservoir pollution serious water flow into constructed wetlands for purification,to achieve the purpose of reducing nutrients and other pollutants.By using Mike21 software,It is simulated the Yuqiao reservoir’s wetland area of the north east area,and establishes the dynamic model of the water.The flow field and water quality change of each plot are obtained through the simulation,It is also to study the processing ability of the polluted materials in the water diversion of the wetland and analyze the change of the constructed wetland’s the flow field and the concentration field under the influence of the inlet,which can provides reference for the design of constructed wetlandsThis paper briefly introduces the general situation of Yuqiao reservoir’s constructed wetland,including the geographical position and climate condition,and analyzes the water pollution load of the Yuqiao reservoir.The basic equations of Mike21 software are introduced,and the simulation of Yanming Lake 2 have found that MIKE21 software has widely applicability to simulate of water power and water quality of constructed wetlands.In order to study the wetland plots’ purification capacity of pollutants in water,it is mainly analyzed the changes of flow field and concentration field in constructed wetland from three aspects:normal circumstances,setting different inlet opening and closing state case,sustained winds of influence situation.The flow field and concentration field distribution of each plot are obtained through the simulation of constructed wetland in different plots.The analysis shows that the distribution of the internal flow field is uniform,and the average velocity is suitable,except the return flow near the inlet.It indicates that constructed wetland has good purification capacity of pollutants in water and it is beneficial for the purification of water pollutants.The simulation of the flow field under different inlet opening and closing conditions indicates that inlet opening and closing of the wetland have great influence on the flow field,but it has gradually stabilized and the overall impact on the wetland water quality change is small;Simulation studies on the flow field and concentration field of wetland with the increase of wind field by two part of the wetland.It shows that when the wetland topographic changes is large,flow field and concentration in wetland has great changes under the influence of wind,but it has little influence on the water quality of wetland.