Complex Under The Condition Of Sudden Water Pollution Accident Emergency Simulation Study

Since the severe Benzene pollution incidents in Songhua River in2005, the degree of attention for Accidental Water Pollution in China has been increasing day by day.After these sudden water pollution accidents happened, they have been not only caused destruction to natural aquatic ecological system, but also polluted the water sources of the downstream urban and force the downstream city to turn off the water plant; not only caused significant socio-economic losses, but also caused panic among the public.Under current background of frequent occurrence of sudden water pollution, the establishment of sudden water pollution emergency warning model which is used for simulating the contaminant transport process in water and the distribution in space and time of contaminant concentration and early warning, in order to improve the pollution risk prevention awareness and strengthen construction of the emergency response capacity, is an important research direction of sudden water pollution emergency response system.According to the mechanism of transportation and transformation of the pollutants in the water, the change of concentration process of pollutants in sudden water pollution accidents can be divided into two parts:one is the contaminants’material transport and diffusion with the flow motion in the space; another one is the decay of the substance concentration in the time by the nature of the pollutants own biochemical processes in the water.1. According to the characteristics of sudden water pollution accidents, the complexity conditions in the sudden water pollution accident simulation and alert have been point out. The accident simulations warning the complicated boundary conditions and complex types of pollutants, complex emergency measures, and these complex conditions, simulation method have been put forward by the accident the uncertainty of the regional water body type, the randomness of characteristics of pollutants, the characteristics of accident emergency measures require in the actual situation. 2. Based on the data of topography, hydrology and pollution load in Shenzhen bay, the sudden water pollution emergency warning model of Shenzhen bay has been developed and validated. The result shows that the model can be well used to simulate water hydrodynamic process and pollutant transport process in Shenzhen Bay. Through the simulation and discussion of contaminant transport and diffusion and flow field in different hydrological conditions, the law of hydrodynamic and pollutant transport in Shenzhen Bay have been analyzed and discussed.3. The effect of complex hydrological conditions on the contaminant transport and diffusion process in sudden water pollution accidents has been discussed by the simulation of the temporal and spatial variation of pollutant concentration of a same water pollution accident in different hydrological conditions. The difference of pollutant concentration in different monitoring cross-sections has been analyzed under different hydrological conditions. The effect of runoff and tide for pollutant concentration changes in the spatial and temporal distribution characteristics in sudden water pollution accident has been discussed. The result shows that the pollutant concentration change processes in the tidal reach of Shenzhen River has been mainly influenced by river runoff in the sudden water pollution accident. So pollutants concentration change process in tidal river can be well controlled by changing the condition of Shenzhen River runoff would be a good way to control.4. Through the analysis of affecting factors for attenuation coefficient of pollutants in water and the discussion of pollutants removal efficiency by different measures within the laboratory level, the relevant research results in the laboratory have been summarized.The kinetic equation of pollutants attenuation coefficient change in different measures has been proposed by the regression analysis method. And then the equation discrete solution method in the contaminant transport model has been analyzed, the model calculation code has been adjusted according to the different mechanism of emergency engineering measures. The kinetic equation of pollutants attenuation coefficient changes and the equation of pollutant transport have been coupled, and a new pollutant transport equation has been obtained which could be drawing the contaminant transport process in different emergency measures. And the cases have been simulated in a sudden water pollution accident when different emergency measures have been taken. The differences of contaminant concentration in different monitoring sections under different engineering emergency measures have been compared with nonparametric statistical hypothesis test method.It suggests that under the conditions setting in this dissertation, the polluted watercourse flushing is a best emergency measure at Luohu section and Buji section; the best emergency measures at Futian section and Shenzhen river section is PACl coagulation.