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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: Developing new bacteria subroutines in the SWAT model

Authors
item Cho, Kyung Hwa
item Pachepsky, Yakov
item Gronewold, Andrew
item Kim, Jung-Woo
item Park, Mi-Hyun
item Kim, Joon Ha

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 4, 2013
Publication Date: N/A

Technical Abstract: Fecal bacteria observations from four different sites in Korea and the US demonstrate seasonal variability, showing a significant relationship with temperature (Figure 1); fecal indicator bacteria (FIB) concentrations are relatively higher in summer and lower in winter , including Stillwater river (STR, Massachusetts), Jumping Run Creek (JRC, North Carolina), Little Cove Creek (LCC, Pennsylvania) and Komacwon Creek (KMC, South Korea). We have also found that FIB concentration does not have an obvious significant relationship with precipitation, although we expected that surface runoff and resuspension driven by precipitation could result in high FIB concentrations. This implies that temperature is the one of key parameters controlling seasonal variability of re-growth or die-off of bacteria in soils and in streams. Existing watershed models, however, have a limitation of simulating this seasonal variability of fecal bacteria. Soil and in-stream bacterial modules of the Soil and Water Assessment Tool (SWAT) model have to be amended to simulate the seasonal variability of bacterial die-off and re-growth . This study develops new bacteria subroutine of SWAT to improve its prediction accuracy and tests the corresponding modules with observations from four different sites. The bacteria modules of SWAT was enhanced by adding critical temperature parameter to simulate die-off and re-growth in soil and in-stream modules. Here, if air temperature is greater than a critical temperature, re-growth is dominant. Otherwise, die-off is dominant. We found that the bacterial modules developed by this study are capable of simulating the seasonal FIB concentration variations.

Last Modified: 12/19/2014
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