Forecasting Safe Distance of a Pumping Well for Effective Riverbank Filtration

Abstract

Riverbank filtration (RBF) is a cost-effective method to pretreat the surface and groundwater supplies. A safe distance of the pumping well is a function of water quality, soil condition, and the rate of pumping. This article reports findings of an analytic element method (AEM) based on logistic function and hydrodynamic groundwater flow. The logistic model was used to find the safe distance of a pumping well from a polluted river with respect to specific log cycle reduction in harmful pathogen concentration, whereas the hydrodynamic equation was used to measure the travel time of a parcel of water to decide the specific location of a production well. Pathogen transport considering dispersion and decay by applying an explicit finite difference scheme was analyzed. In this article, pathogen transport in groundwater was simulated using a developed model called LIFI-PATRAM that integrated an AEM flow solution with a pathogen transport model. The variation of pathogen concentration with distance at different times was also analyzed for the specific pumping rate. To achieve the objective of limiting pumping rate, the desired reduction of pathogen concentration was evaluated. The findings revealed that the variation of logarithmic concentration of pathogen with distance became linear under hydrodynamic equilibrium condition, which helped to forecast the appropriate location of a pumping well.