MODELING THE FATE AND TRANSPORT OF PATHOGENS IN A WATERSHED USING DISCRETE VOLUME METHOD

Discrete volume method (DVM) previously used in the field of water distribution networks is tested for application in modeling the fate and transport of fecal coliform in streams. The method along with few assumptions is used to develop a simulation model to handle the transport and decay of fecal coliform loads in streams. Processes responsible for decay and wash-off of fecal coliform in streams and watershed are modeled as first-order decay processes in the simulation model. The model considers both point and non-point sources as pollution sources. The parameters in the simulation model are optimized using genetic algorithms (GA) with real coding scheme. Two 8-digit USGS watersheds that comprise of several 11-digit USGS HUC watersheds in the Big Sandy region of southeastern Kentucky are used to assess the applicability of the model. Straight pipes and failing septic systems are identified as two main sources of pathogen impairment in this region. Preliminary results from the application of the model to real-life case study suggest that DVM based simulation model can be used to estimate relative contribution of pathogen loads from different watersheds and also to assess water quality management alternatives by reduction of point and non-point sources.