Capturing microbial sources distributed in a mixed-use watershed within an integrated environmental modeling workflow

Authors: WHELEN, GENE - Environmental Protection Agency (EPA); KIM, KEEWOK - University Of Idaho; PARMAR, RAJBIR - Environmental Protection Agency (EPA); LANIAK, GERARD - Environmental Protection Agency (EPA); WOLFE, KURT - Environmental Protection Agency (EPA); GALVIN, MICHAEL - Environmental Protection Agency (EPA); MOLINA, MARIROSA - Environmental Protection Agency (EPA); Pachepsky, Yakov; DUDA, PAUL - Aqua Terra Consultants; ZEPP, RICHARD - Environmental Protection Agency (EPA); PRIETO, LOURDES - Environmental Protection Agency (EPA); KINZELMAN, JULIE - Collaborator; KLEINHEINZ, GREGORY - University Of Wisconsin; Borchardt, Mark

Submitted to: Journal of Environmental Modeling and Software
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2017
Publication Date: 1/1/2018
Citation: Whelen, G., Kim, K., Parmar, R., Laniak, G., Wolfe, K., Galvin, M., Molina, M., Pachepsky, Y.A., Duda, P., Zepp, R., Prieto, L., Kinzelman, J., Kleinheinz, G., Borchardt, M.A. 2018. Capturing microbial sources distributed in a mixed-use watershed within an integrated environmental modeling workflow. Journal of Environmental Modeling and Software. 99:126-146.

Interpretive Summary: Models became the widespread tool for the microbial water quality research and management. The most efficient use of models is based on multiple simulations with realistic scenarios. The critical issue in such simulations is providing credible input data for such simulations. Simulation results are known to be most sensitive to microbial loading rates. Currently estimating the loading rates is extremely labor- and time–consuming. The objective of this work was to develop the efficient loading rate simulator that could provide loading rate values for the major animal sources and environmental conditions that can be encoutered in microbial water quality modeling. We found that the current state of knowledge is sufficient for the development of such versatile tool for microbial loading rates associated with 1) land-applied manure on undeveloped areas from domestic animals; 2) direct shedding (excretion) on undeveloped lands by domestic animals and wildlife; 3) urban or engineered areas; and 4) point sources that directly discharge to streams from septic systems and shedding by domestic animals. The underlying equations, program realization, data sources, and an example of applications are presented in the manuscript. Results of this work are expected to be used in environmental microbial assessments by the variety of government and consultant users who can take the advantage of the accessibility and availability of microbial water quality modeling inputs.

Technical Abstract: Many watershed models simulate overland and instream microbial fate and transport, but few provide loading rates on land surfaces and point sources to the waterbody network. This paper describes the underlying equations for microbial loading rates associated with 1) land-applied manure on undeveloped areas from domestic animals; 2) direct shedding (excretion) on undeveloped lands by domestic animals and wildlife; 3) urban or engineered areas; and 4) point sources that directly discharge to streams from septic systems and shedding by domestic animals. A microbial source module, which houses these formulations, is part of a workflow containing multiple models and databases that form a loosely configured modeling infrastructure which supports watershed-scale microbial source-to-receptor modeling by focusing on animal- and human-impacted catchments. A hypothetical application – accessing, retrieving, and using real-world data – demonstrates how the infrastructure can automate many of the manual steps associated with a standard watershed assessment, culminating in calibrated flow and microbial densities at the watershed’s pour point.