Research On The Simulation Of Environmental Emergencies In Fenhe Reservoir

Owing to the common problem of water shortage in arid areas of northern China,the reservoir has become the main water source for many cities.The environmental emergencies in reservoirs not only threaten the safety of drinking water,but also affect the stability of cities and trigger social public crisis.Mainly concentrating on the oceans and rivers,the environmental emergencies research on reservoirs is relatively scarce at home and abroad,and the systematic theoretical results guiding the emergency response have not yet been formed.There is a complex industrial layout and a well-developed surrounding road network in the control catchment of Fenhe reservoir,the largest source of drinking water in Shanxi Province.Once the environmental emergencies occurred,the residents' drinking water safety of provincial capital Taiyuan and the surrounding cities would be seriously affected.Therefore,it is necessary to conduct a further research on the environmental emergencies in Fenhe reservoir.Applying the method of environmental system analysis,in this paper,Fenhe reservoir was taken as the research object and the research technical route was determined.Based on the date,the field survey was conducted to identify the sources and the substances of environmental risk in reservoirs.The two-dimensional hydrodynamic and water quality coupling model of Fenhe reservoir was built.Different scenarios were set to simulate the migration diffusion and concentration distribution of pollutants.The emergencies disposal of Fenhe reservoir would be guided by the research results.The research results of this paper are mainly reflected in:(1)Applying the method of systematic analysis,with a synthesis of the hydrodynamic model and the substance transport and diffusion model,a set of technical system,which disposed the environmental emergencies in reservoirs qualitatively and quantitatively,was formed according to the characteristics of water environment in the arid areas of northern China.(2)Getting the geographic location of Fenhe reservoir through the field research,the coordinates of the edge point were determined with the aid of GPS positioning and remote sensing image data,and the reservoir boundary was digitized using GIS technology.Establishing a triangular mesh system,and then importing the water depth files,the numerical terrain was obtained by means of triangular interpolation,boundary extension and multiple smoothing dispose.The time series of water inlet and outlet,evaporation rainfall,wind speed and wind direction of the reservoir was generated.Building the hydrodynamic and water quality coupling model,the parameters were calibrated and the model was verified to determine parameters value finally.(3)Considering the stationary and mobile sources,the potential environmental risk sources in the upper reaches of Fenhe Reservoir and surrounding roads were identified.It was concluded that the stationary sources mainly originated from the industry and enterprise,and the mobile sources mainly stemmed from the traffic accidents.Then the representative stationary risk sources,mobile risk sources and their risk substance were screened out.(4)The factors of the incident source,the initial concentration,the entrance of emission,the wind direction and the wind speed which affected the diffusion path,the diffusion range and the concentration distribution of pollutants were considered respectively.Setting a variety of scenarios to carry out the numerical simulation of environmental emergencies in Fenhe reservoir taking advantage of the two-dimensional hydrodynamic and water quality coupling model which had already been built.The migration diffusion and concentration distribution of pollutants in different scenarios were revealed.(5)These following results can be obtained by the simulation of environmental emergencies:1)When the incident source,the entrance of emission,the wind direction and the wind speed are unchanged,with the increase of initial concentration of pollutants,the diffusion range of pollutants is constant,but the excessive area of the reservoir increases;the concentration of the pollutants is positively correlated with the initial concentration.2)When the incident source,the entrance of emission and the initial concentration are unchanged,the pollutants spread radially taking the spill site as a center under the condition of no wind.The diffusion path of pollutants changes and the diffusion rate increases under a windy condition.The diffusion path is determined by the wind direction,and the diffusion range is determined by the wind speed.When the wind speed is constant,the diffusion rate under the northwest wind is greater than the southwest wind.When the wind direction is constant,both the diffusion area and the excessive area are approximately linear with the wind speed.3)When the incident source,the initial concentration,the wind direction and the wind speed are unchanged,the diffusion range of eastern entrance is the largest,and the diffusion range of the main stream entrance of northern upstream is greater than the western river entrance.(6)Based on the simulation results of environmental emergencies in Fenhe reservoir,the relationship between the diffusion path,the diffusion distance,the diffusion range,the pollution level and the entrance,the initial concentration,the wind direction,the wind speed was determined under different conditions.The forecast table of the emergencies was established,which can query the migration diffusion and concentration distribution of pollutants quickly.Emergency control measures of the environmental emergencies were put forward in an exploratory way.With a synthesis of the hydrodynamic model and the substance transport and diffusion model in this paper,the migration diffusion and concentration distribution of pollutants of the environmental emergencies in Fenhe reservoir are systematically analyzed.It would guide the migration path,the diffusion range and the concentration distribution once the environmental emergencies occurred.It is of certain practical significance which is explored in this paper.