Multimodel, Multiple Watershed Examination of In-Stream Bacteria Modeling

Abstract

Excessive bacteria levels are a major water-quality problem in U.S. water bodies, and this study looked at the use of watershed-scale computer models to predict in-stream bacteria concentrations. The study site was the Little River Experimental Watershed (LREW) in Tifton, Georgia, and fecal coliform fate and transport models were built for four of the LREW subwatersheds over the period January 1996–December 2002. Three models were examined: HSPF, the soil and water assessment tool (SWAT), and the characteristic concentration (CC) model based on the principles of hydrograph separation. It was found that the most sensitive HSPF and SWAT water-quality parameters were associated with the in-stream bacteria processes, whereas parameters relating to terrestrial activity varied from sensitive to completely insensitive. Model performance was evaluated using the Nash–Sutcliffe statistic, and HSPF, SWAT, and the CC model performed comparably while showing distinct performance capabilities.