Analysis Of Movement Law Of Water Pollutants In Nanwang Reservoir Diversion Project And Emergency Response To Sudden Incident

In order to study the migration law of water pollutants in water conveyance channels and to carry out effective early warning and emergency disposal of sudden water pollution accidents along the route,this paper takes the Gaotang section of Nanwang reservoir water diversion project as the research object,the water environmental capacity of the research object under different conditions is calculated by the formula method,and the process of the decay of water pollutants,early warning and emergency of sudden water pollution accidents under different conditions are studied and analyzed by the method of numerical simulation.Specific research content and conclusions are as follows:In this paper,the different generalization methods of the sewage outfall in the one-dimensional water environmental capacity calculation model are analyzed,on this basis,a multi-point generalized water environmental capacity calculation model is deduced.According to the actual distribution of pollution sources along the Gaotang section of Nanwang reservoir diversion project,the water environmental capacity of the water mains under three conditions of water,flat water,dry water(hereinafter referred to as different water periods)is calculated by using different water environmental capacity calculation models.The calculation result shows that the water environmental capacity calculated by the three-point generalized water environmental capacity calculation model is smaller than that calculated by the vertex generalized water environmental capacity calculation model and is larger than that calculated by the mid-point generalized water environmental capacity calculation model.In addition,it can be seen that the water environmental capacity of the water mains in different water periods is quite different,it is necessary to reasonably determine the water environmental capacity according to the water conveyance conditions.The non-constant hydrodynamic equation is coupled with the one-dimensional convective diffusion water quality equation.The coupling mathematical model is used to simulate the migration and degradation of typical water pollutants in different water periods.Under the simulation results,it can be seen that the concentration of pollutants in the same section is quite different under different water period conditions,the concentration line of water pollutants from the head to the end of the mouth is jagged intermittently,which there are three large increases,in line with actual pollutant emissions.The water of trunk meets the surface water class IV water quality standard.Analyzing and determining the prone area of sudden water pollution accident along the main channel,the different water pollution accidents are established,and the processes of migration and decay of the characteristic pollution zone under different water periods are simulated by using the coupled water quality model,the simulation results show that the concentration of contaminated zone is roughly symmetrical parabolic,from the sharp type of upstream gradually transition to the chunky type of downstream,the concentration peak will gradually cut after the accident broke out.For the same control section,the influence time of pollutants on the cross-section and the period of the concentration of water pollutants exceeds the target water quality standard(hereinafter referred to as the time of unavailable water)in different water periods are very different,but the impact of water periods on the time which from the accident to the concentration of water pollutants reaches to the target water quality standard(hereinafter referred to as the warning time)is not very significant.For the same period of time,the warning time and the time of unavailable water of different sections are different,For the warning time,the downstream section closer to the accident point is shorter than the downstream section at a distance from the accident point.The time of unavailable water of the former is longer than the latter in the wet period,but with the transition from the wet period to the dry season,the time of unavailable water of the latter section can exceed the former.Analyzing the emergency disposal of two sudden water pollution accidents,using the method of a variety of emergency measures in combination to deal with the accident one,using the emergency treatment of water diversion to deal with the accident two,and the emergency effect of the latter was simulated by using the constructed water quality model.After determining the reasonable water diversion point and diversion time,which can effectively reduce the concentration of the pollution zone in the main canal,and with the increase in water diversion,the concentration of the contaminated zone of canal tail can be basically satisfied in the surface water class V water quality standard value below.