Assessment of Groundwater Vulnerability in Changwon, Korea

In Book-Myeon and Daesan-Myeon in Changwon city, South Korea, riverbank filtration and groundwater pumping plants have been constructed and pumping wells have been operated to extract water from the subsurface. To keep the quality of water that is extracted from those pumping wells to a proper level, contaminant discharge from the background area is needed to be controlled. Knowing the vulnerability of groundwater to contaminants is important for this. The adjoint backward equation of advection dispersion equation is applied in assessing the vulnerability of groundwater. The location and travel time probability of contaminants to a pumping well is derived from the adjoint backward equation. The backward probability model has an advantage that it is physically based on the process of contaminant transport. It can be used to predict the impact of contamination event to a well. With the backward probability model one can have information about the travel time and location of the contaminant discharged at any point in the field site to the pumping well. This method is applied to Book-Myeon and Daesan-Myeon to assess the vulnerability of groundwater from pumping wells to contaminant. From the result of the backward probability model, the information about the location of high risk and the acceptable quantity of contaminant discharge from the background area are given. This information can be useful in setting the better management plan to protect the water quality of the water supply plants.