Water Environment Dynamics Simulation Research And Emergency Water Pollution Incidents Based On EFDC-Miyun Resorvior As An Example

Miyun Reservoir is the largest and the only surface drinking-water sources inBeijing. With the rapid development of economy, Miyun Reservoir environmental ispolluted. The quality of water trends down. Master the basic hydrologicalcharacteristics, the reservoir area mechanism of water environment, do somesimulation and predicted warnings, to curb deterioration of Miyun Reservoir waterhas a certain guiding significance, to provide relevant technical support for thegovernance of reservoir environmental.In this paper, through collecting the measured data of reservoir area and thesurrounding, generalized the simulation range of time and space in the studied area,build EFDC model of Miyun Reservoir two-dimensional hydrodynamic-waterquality model. Through the Miyun Reservoir water dynamic model, obtained the goodwater level simulation results, the average error is about0.61%. Temperaturesimulation results objectively reflect the temperature change of the four seasons inMiyun Reservoir, explains the reason that in the spring and winter the center ofreservoir water temperature is low, and in the summer and fall is high.Based on hydrodynamic model, using2007-2008water quality data of MiyunReservoir build model the water quality model,the simulation results show that::each water quality index trends consistent with the measured values, the simulation isgood, the average error is within acceptable range: the average error of DO is13.34%,the average error of Ammonia Nitrogen is12%, the average error of Total Nitrogenis11.43%, the total average error of Total Phosphorus is12.34%.Simulation resultsshow that in2008, each water quality index trends consistent with the measuredvalues, and the simulation is better than2007, the average error is within acceptablerange. The simulation can meet the forecast, early warning and other technicalrequirements.On the basis of debugged water quality model, set up two situations, one is theinstantaneous discharge of pollutants and the other is the continuous discharge ofpollutants. Selected the attenuation coefficient of1e-8,1e-7,5e-7e, using themanual processing way and not considering the situation of attenuation coefficient forcomparison, found that:(1) the instantaneous discharge of the accident point is locatedinside the reservoir, the driving force of contaminant plume migration are mainlycomposed of wind.In the eastern and southern of the reservoir, the contaminant plumespread by vortex movement. While the continuous discharges near the accident pointis located in the inflow, the inflow water as the main driving force affecting the solutetransport.(2) The instantaneous discharge under the condition of considering threedifferent attenuation coefficients. As the attenuation coefficient increases, the peaks ofconcentration at the same time show the tendency of decrease.(3) Considering theattenuation coefficient, the contaminant plume range declined obviously.To sum up, it is certain feasibility to using EFDC model to simulate the MiyunReservoir water environment and warning the pollution incidents. This model canprovide technical support for Miyun Reservoir management,and control works.