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United States Department of Agriculture

Agricultural Research Service

Research Project: PATHOGEN FATE AND TRANSPORT IN IRRIGATION WATERS

Location: Environmental Microbial and Food Safety Laboratory

Title: The modified SWAT model for predicting fecal coliform in the Wachusett Reservoir Watershed, USA

Authors
item Cho, Kyunghwa
item Pachepsky, Yakov
item Kim, Joon Ha
item Kim, Jung-Woo
item Park, Mi-Hyin

Submitted to: Water Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 29, 2012
Publication Date: July 9, 2012
Repository URL: http://handle.nal.usda.gov/10113/56579
Citation: Cho, K., Pachepsky, Y.A., Kim, J., Kim, J., Park, M. 2012. The modified SWAT model for predicting fecal coliform in the Wachusett Reservoir Watershed, USA . Water Research. 46:4750-4760.

Interpretive Summary: Fecal contamination of surface waters has been implicated in human illness. Infection can occur from either consumption of fresh produce irrigated with contaminated water or from receational use of contaminated water. Both sources and inactivation rates of pathogens and indicator organisms need to be known in order to predict and mitigate the contamination of stream waters. Modeling presents a useful tool for evaluating the significance of different microbial sources. We modified the SWAT model to simulate and assess the relative significance of microbial input from beaver populations, and to estimate dieoff caused by the solar radiation. The modified SWAT model was applied to the Wachusett Reservoir Watershed in Massachusetts. Accounting for solar radiation and the seasonal input of microbes from beaver feces appeared to be essential in order to simulate the observed fecal coliform concentrations. This work is important to researchers and practitioners in the fields of watershed management and irrigation in that it provides tools for improvement of prediction accuracy and mitigation practices regarding microbial safety of stream waters.

Technical Abstract: Fecal contamination has been an issue for water quality because fecal coliform bacteria are used as an indicator organism to detect pathogens in water. In order to assess fecal contamination in the Wachusett Reservoir Watershed in Massachusetts, USA, the Soil and Water Assessment Tool (SWAT), a commonly used watershed model was used. The SWAT had been augmented with the bacterial fate and transport subroutine, where bacteria die-off is the only in-stream process, and the bacteria module was modified in this study to include solar radiation-associated die-off and the contribution of wildlife. The Latin-Hypercube one at a time (LH-OAT) was used for the sensitivity analysis of hydrologic and modified bacteria modules in the SWAT model. The result demonstrates that solar radiation is one of the most significant fate factors of fecal coliform. A water temperature associated function was added to consider the contribution of beaver activity to fecal contamination in the watershed, resulting in improved prediction accuracy. The modified SWAT model provides an improved estimate of bacteria from the watershed. Our approach will be useful for simulating bacterial concentrations to provide predictive and reliable information of fecal contamination thus facilitating the implementation of effective watershed management.

Last Modified: 10/22/2014