Slope effects on SWAT modeling in a mountainous basin

Author (s): Yacoub, C. and Pérez-Foguet, A.
Journal: Journal of Hydrologic Engineering

Volume: 18, Number: 12
Pages: 1663 – 1673
Date: 2013

The soil and water assessment tool (SWAT) is a distributed basin model that includes the option of defining spatial discretization in terms of terrain slope. Influence of terrain slope in runoff results from mountain basins is a determining factor in its simulation results; however, its use as a criterion for basin discretization and for the parameter calibration has not been analyzed yet. In this study, this influence is analyzed for calibrations using two different cases. Ten discretization cases were carried out to evaluate the relative importance of slope discretization as compared to other discretization criteria. Data from 1999 to 2005 were used for model calibration, and those from 2006 to 2009, for model validation. Parameter identification and specification were performed with the the combined latin hypercube and one-factor-at-a-time (LH-OAT) and the shuffled complex evolution-uncertainty analysis methods (SCE-UA), respectively, both of which are included in ArcSWAT2005. All cases resulted in very good statistical values, with the Nash-Sutcliffe efficiency coefficient of 0.82–0.85, a percent bias of 2–10%, and the observations standard deviation ratio of 0.4?0.3. More realistic calibrated parameters were found when terrain slope variation was not included in the spatial discretization criteria. The inclusion of slope did not significantly improve simulations results when a good set of parameters was used but it did enhance the calibration when a reduced number of sub-basins was used.



	author = {Yacoub, C. and P\’erez-Foguet, A.},
	title = {Slope Effects on SWAT Modeling in a Mountainous Basin},
	journal = {Journal of Hydrologic Engineering},
	volume = {18},
	number = {12},
	pages = {1663–1673},
	year = {2013},
	doi = {10.1061/(ASCE)HE.1943-5584.0000756},
	URL = {http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29HE.1943-5584.0000756}