Groundwater Pollution Risk Assessment Based On Process Simulation Method

Since the groundwater pollution risk assessment was put forward to now, theassessment method has experienced a series of changes. The tendency is mainlyshown from simple, qualitative, inexpensive, indexing assessment to complex,quantitative, costly, numerical modeling assessment. Now from all kinds of riskassessment methods, index method and process method are the most widely usedmethods. Index method is easy to use and the data needed is easy to get, what’s more,it can give out a solution of classification, therefore, it is very popular. Index methodcan figure out the high risk subarea in a large region and is suitable for assessmentand optimization of decisions and analysis on a regional scale.Compared with index method, process method focuses on the pollution risk tothe groundwater in a field from some specific pollution sources. This method canpredict the sphere and the duration time of the pollution plume in the future under allkinds of condition based on the groundwater flow and contaminant transportsimulation. The risk level can be ranked according to the distribution of contaminantconcentration and the influence sphere. In this way, the distribution of risk levels inthe target field can be well described.As an example of a field where a new factory is located, this paper use processsimulation method to assess the groundwater pollution risk of the field. The pollutionrisk level of the groundwater around the new factory is estimated under the presentmanufacturing technology and product scale. Build up a numeric model on the basisof the hydrogeologic condition and the characteristic of pollution source, andcalculate the transport and attenuation process of the pollution plume in groundwater.With a standard of the Ⅲ class concentration limit in water quality standard, pollutedzone and unpolluted zone are distinguished. Then we observe the distribution andchange of polluted zone in the environment, especially the location relationship ofpolluted zone and environmental sensitive zone. Finally classify the groundwaterpollution risk level based on the observation. It’s shown in the simulation solution that the groundwater pollution risk level around the factory is medium.Practical field application research indicate that process method has importantapplication value in groundwater pollution risk assessment for fields or small areas.