Numerical Simulation Of Shahu Lake Water Environment Based On MIKE21

The ecological function of Shahu Lake is crucial.With the continuous development of tourism resources in Shahu,the quality of water environment has been declining year by year,and environmental problems have intensified.In order to study the changes of the hydrodynamic field and water quality field in Shahu Lake,the water environment factors of Shahu Lake water body were carried out in April 2017(spring),July(summer),October(autumn)and January 2018(winter).Sampling and measurement,analysis of its spatial and temporal distribution characteristics;using principal component analysis to study the main water environmental factors affecting Shahu Lake;using grey correlation method and comprehensive pollution index method to comprehensively evaluate the water environment of Shahu Lake;using MIKE21 module to establish sand lake water The dynamic model and water quality model simulate the changes of hydrodynamic and water quality fields in Shahu in 2017,providing basic theoretical data for the environmental protection,protection and sustainable development of Shahu Lake.The main results of this study are as follows:(1)Principal component analysis method selects four principal components.The contribution rates of principal component 1 and principal component 2 are 29.02%and 27.33%,respectively.Both of them play a major role in water quality,and the water environmental factors include chlorophyll a and BOD5,TN,nitrate nitrogen,TP,pH;according to the conprehensive score of the water environment factor of Shahu Lake,the main factors affecting the water environment of Shahu Lake can be determined as TP,chlorophyll a,pH,CODCr,BOD5,NH3-N,nitrate state.Nitrogen,nitrite nitrogen,TN.Comprehensive analysis,water,environmental factors such as TP,chlorophyll a,pH,CODCr,BOD5,NH3-N have great influence on the water quality of Shahu Lake.Organic matter,phytoplankton and nitrogen and phosphorus nutrients play a major role in the Shahu water body,causing sand.The main reason for the change in lake water quality.(2)The water quality grades of the four seasons of spring,summer,autumn and winter in Shahu Lake are:Class IV,Class V,Class V and Class V.From the comprehensive pollution index of Shahu Lake,the pollution of Shahu Lake is relatively serious.The temporal and spatial variation trend between Shahu sample points is not large,and it is rising in spring-summer,reaching the naximum in summer and the most serious pollution.(3)The basic data such as topography,wind field,rainfall and evaporation required for the hydrodynamic model were collected to establish the hydrodynamic model of the Shahu Lake,and the parameter determination and model verification were carried out to finally obtain the Shahu hydrodynamic field(water level,flow rate,etc.).Changes.Based on the hydrodynamic model,six main water quality factors such as chlorophyll a,BOD5,TP,CODa,DO and NH3-N were selected as state variables,and the basic data input,water quality parameter determination and model verification were constructed.The sand lake water quality model,the measured values of the model agree well with the predicted values.Within the allowable range of error,the water quality model can accurately simulate the change of the Shahu water quality field.Based on this simulation,the change of water quality in Shahu Lake can be analyzed and predicted,which plays an important role in predicting the water environment control of Shahu Lake.