Impact of Spatial Discretization of Hydrologic Models on Spatial Distribution of Nonpoint Source Pollution Hotspots
Publication: Journal of Hydrologic Engineering
Volume 21, Issue 12
Abstract
The soil and water assessment tool (SWAT) was used to investigate the effects of hydrologic response unit (HRU) thresholds (0–20%) on predictions of multiple variables by calibrated and uncalibrated models in a urban watershed in the U.S. Mid-Atlantic region. Surface runoff, discharge, sediment yield, and nutrient yield were simulated in stream and on land, and used to spatially identify hotspots for each constituent. SWAT2012 was able to produce accurate discharge and nitrogen estimates that were not sensitive to HRU thresholds. HRU thresholds significantly affected sediment and phosphorus predictions in calibrated and uncalibrated models. Constituent hotspots identified by an uncalibrated model with a 0% HRU threshold were found to be acceptable for the urban watershed under study, except for sediment. Hotspots identified with calibrated models, with HRU thresholds of 5% or less, fit with the identification of on-land sediment and nutrient hotspots. These findings suggest that researchers should carefully consider HRU thresholds when predicting on-land variables of small urban watersheds similar to the watershed in this study when using SWAT.
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Acknowledgments
The authors thank USEPA for providing financial support (Grant Number: R835284). This work is part of the research project Sustainable Community Oriented Stormwater Management (S-COSM): A Sensible Strategy for the Chesapeake Bay, which aims to efficiently improve urban stormwater conditions by increasing adoption of best management practices, specifically for targeted hotspots, via community-based participatory research. The authors also thank Stephen Reiling of the DC Department of the Environment for providing water quality data in the Watts Branch watershed.
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Information & Authors
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Published In
Journal of Hydrologic Engineering
Volume 21 • Issue 12 • December 2016
Copyright
© 2016 American Society of Civil Engineers.
History
Received: Jan 11, 2015
Accepted: Jul 12, 2016
Published online: Aug 16, 2016
Published in print: Dec 1, 2016
Discussion open until: Jan 16, 2017
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