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Modeling Source-specific Fecal Coliform Bacteria using SWAT/Microbial sub-model
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Paper number 052126, 2005 ASAE Annual Meeting . (doi: 10.13031/2013.19843) @2005Authors: Prem Parajuli, Kyle R. Mankin, Philip L. Barnes
Keywords: Fecal coliform bacteria, rainfall, runoff, SWAT, watershed
Water-quality impairments due to fecal bacteria in surface water often result from the
non-point source pollution, including land-applied animal manure, septic tank failure, and grazing
operations. Several models have been developed during the past two decades to model the
movement of bacteria from agricultural land to the stream (MWASTE, COLI, SEDMOD, HSPF, and
SWAT). Limited research has verified these models for simulating bacterial concentrations. All of
these models simulate bacterial concentrations based on Chicks Law; most assume steady-state
conditions and are not process-based. The objective of this research is to calibrate and verify
SWAT/Microbial sub-model using source specific bacterial data. The bacterial loadings for each
source were calibrated separately using the fraction of animal or human contribution to bacterial
samples based on source tracking analysis.
The model was calibrated using coefficient of determination (R2) and Nash Sutcliffe Efficiency
Index (EI) at the sub-watershed scale for each bacterial source. The results of this research was
able to demonstrate the use of SWAT for modeling fecal bacteria and help refine procedures for
estimating livestock and septic system input parameters.