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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #319812
Title: Modeling seasonal variability of fecal coliform in natural surface waters using the modified SWAT

Author
item CHO, KYUNG HWA - Gwangju Institute Of Science And Technology
item Pachepsky, Yakov
item KIM, MINJEONG - Gwangju Institute Of Science And Technology
item PYO, JONGCHEOL - Gwangju Institute Of Science And Technology
item PARK, MI-HYUN - University Of Massachusetts
item KIM, JUNG-WOO - Korea Atomic Energy Research Institute (KAERI)
item KIM, JOON HA - Gwangju Institute Of Science And Technology

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2015
Publication Date: 2/16/2016
Citation: Cho, K., Pachepsky, Y.A., Kim, M., Pyo, J., Park, M., Kim, J., Kim, J. 2016. Modeling seasonal variability of fecal coliform in natural surface waters using the modified SWAT. Journal of Hydrology. 535:377-385.

Interpretive Summary: Microbial dynamics in watersheds is of paramount importance for the microbial quality of irrigation and recreational waters. Modeling with the USDA-ARS SWAT model is recommended for designing diagnostics, monitoring of microbial quality of freshwater sources, and assessment of management practices to control quality. The SWAT model currently simulates microbial die-off in waters as a function of temperature. However, other factors exist that cause well expressed seasonality in die-off. We tested the hypothesis that defining seasonal temperature functions can improve the model performance. We tested this hypothesis with high quality monitoring datasets from Pennsylvania, Massachusetts, North Carolina, and Korea, and found that indeed modeling results can be statistically significantly improved. The results of this work can be of use for the large group of microbial water quality specialists, regulators, ad managers in that they offer substantial improvement in modeling for environmental management design and evaluation.

Technical Abstract: Fecal coliforms are indicators of pathogens and thereby, understanding of their fate and transport in surface waters is important to protect drinking water sources and public health. We compiled fecal coliform observations from four different sites in the USA and Korea and found a seasonal variability with a significant connection to temperature levels. In all observations, fecal coliform concentrations were relatively higher in summer and lower during the winter season. This could be explained by the seasonal dominance of growth or die-off of bacteria in soil and in-stream. Existing hydrologic models, however, have limitations in simulating the seasonal variability of fecal coliform. Soil and in-stream bacterial modules of the Soil and Water Assessment Tool (SWAT) model are oversimplified in that they exclude simulations of alternating bacterial growth. This study develops a new bacteria subroutine for the SWAT in an attempt to improve its prediction accuracy. We introduced critical temperatures as a parameter to simulate the onset of bacterial growth/die-off and to reproduce the seasonal variability of bacteria. The module developed in this study will improve modeling for environmental management schemes.