Inversion Identification Of Organic Pollution Sources In A Typical Site

With the rapid development of society and the progress of science and technology,the intensity of human activities has increased significantly,and the groundwater environment has suffered serious pollution,especially the organic pollution of groundwater.It is difficult to control groundwater organic pollution,the distribution area is wide and the source of pollution is not clear.Even if the source of pollution is completely eliminated,it will take decades or even decades for water quality to recover,depending on the aquifer’s self-purification capacity.Therefore,controlling the pollution source and reducing the threat of the pollution source to the groundwater system is the focus and key of the control and prevention of organic groundwater pollution,and the research on the inversion and identification of groundwater pollution source becomes particularly important.This paper takes a typical chemical area of lanzhou city,gansu province as an example,meteorological and field geological and hydrogeological information collection,analysis of hydrogeology and groundwater flow field characteristics,the source items,boundary conditions,the structure of the aquifer are generalized and establishes a hydrogeological conceptual model,determines its for heterogeneity on the second floor of the three dimensional non steady flow.The MODFLOW module in Visual MODFLOW software is used to establish the groundwater flow model.The water level data of observation holes and groundwater flow field are selected to identify and verify the water flow model.The result shows that the average fitting error of the water level in the observation hole is less than0.15 m,and the fitting degree of the simulated flow field and the measured flow field is good,and the flow model has high reliability.Basing on the flow model,we analysis the water quality monitoring data,determine benzene for typical pollution factor,build the solute transport model.chose the dispersion degree,porosity,apply the method of control variable,set up the range of plus or minus10%,plus or minus 20% four parameters,the introduction of sensitivity index and sensitivity analysis two parameter sensitivity index control within 5.7% and 14.6%,respectively,showed that benzene pollution plume migration response law of diffusion of dispersion degree and porosity is better,the initial values of parameters can be as the inversion model of parameter values.With the aid of solute transport model,set up different pollution situation,try to estimate method inversion to determine leakage of oil reservoir pollution concentration,introducing the average relative error of the inversion results are measured and the results show that leak leakage concentration at point1,2,45mg/L respectively,55mg/L,the minimum error value,to determine the concentration of pollution concentration of leak point and set up according to the results of the inversion of plume in the aquifer distribution range,the conclusion obtained is the typical area will provide referential basis for the pollution control and prevention and control.