Revisiting SWAT as a Saturation-Excess Runoff Model
1
Biological and Environmental Engineering, Cornell University, Ithaca, NY 14853, USA
2
New York City Department of Environmental Protection, Kingston, NY 12401, USA
3
Currently at National Institute of Water & Atmospheric Research (NIWA), Hillcrest, Hamilton 3251, New Zealand
4
Faculty of Civil and Water Resources Engineering, Bahir Dar Institute of Technology, Bahir Dar 6000, Ethiopia
*
Author to whom correspondence should be addressed.
Water 2019, 11(7), 1427; https://doi.org/10.3390/w11071427
Received: 6 May 2019 / Revised: 28 June 2019 / Accepted: 8 July 2019 / Published: 11 July 2019
(This article belongs to the Special Issue Hydrological Modelling and Remote Sensing: Selected Papers from the 2017 and 2018 SWAT International Conferences)
The Soil Water Assessment Tool (SWAT) is employed throughout the world to simulate watershed processes. A limitation of this model is that locations of saturation excess overland flow in hilly and mountainous regions with an impermeable layer at shallow depth cannot be simulated realistically. The objective of this research is to overcome this limitation with minor changes in the original SWAT code. The new approach is called SWAT-with-impervious-layers (SWAT-wil). Adaptations consisted of redefining the hillslope length, restricting downward percolation from the root zone, and redefining hydrologic response units (HRUs) such that they are associated with the landscape position. Finally, input parameters were chosen such that overland flow from variable saturated areas (VSAs) corresponds to the variable source interpretation of the Soil Conservation Service (SCS) curve number runoff equation. We tested the model for the Town Brook watershed in the Catskill Mountains. The results showed that the discharge calculated with SWAT-wil agreed with observed outflow and results simulated with the original SWAT and SWAT-hillslope (SWAT-HS) models that had a surface aquifer that transferred water between groups of HRUs. The locations of the periodically saturated runoff areas were predicted by SWAT-wil at the right locations. Current users can utilize the SWAT-wil approach for catchments where VSA hydrology predominates.
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Keywords:
hardpan; lateral flow; saturation excess runoff; SWAT; variable source area
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MDPI and ACS Style
Steenhuis, T.S.; Schneiderman, E.M.; Mukundan, R.; Hoang, L.; Moges, M.; Owens, E.M. Revisiting SWAT as a Saturation-Excess Runoff Model. Water 2019, 11, 1427. https://doi.org/10.3390/w11071427
AMA Style
Steenhuis TS, Schneiderman EM, Mukundan R, Hoang L, Moges M, Owens EM. Revisiting SWAT as a Saturation-Excess Runoff Model. Water. 2019; 11(7):1427. https://doi.org/10.3390/w11071427
Chicago/Turabian StyleSteenhuis, Tammo S.; Schneiderman, Elliot M.; Mukundan, Rajith; Hoang, Linh; Moges, Mamaru; Owens, Emmet M. 2019. "Revisiting SWAT as a Saturation-Excess Runoff Model" Water 11, no. 7: 1427. https://doi.org/10.3390/w11071427
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