Title: | A new physically-based spatially-distributed groundwater flow module for SWAT+ |
Authors: | Bailey, R.T., K. Bieger, J.G. Arnold and D.D. Bosch |
Year: | 2020 |
Journal: | Hydrology |
Volume (Issue): | 7(4) |
Pages: | |
Article ID: | 75 |
DOI: | 10.3390/hydrology7040075 |
URL (non-DOI journals): | |
Model: | SWAT+ (modified) |
Broad Application Category: | hydrologic only |
Primary Application Category: | groundwater and/or soil water impacts/processes |
Secondary Application Category: | model and/or data interface |
Watershed Description: | 327 km^2 Little River Experimental, a tributary of the Upper Suwannee River located in south-central Georgia, U.S. |
Calibration Summary: | |
Validation Summary: | |
General Comments: | |
Abstract: | Watershed models are used worldwide to assist with water and nutrient management
under conditions of changing climate, land use, and population. Of these models, the Soil and
Water Assessment Tool (SWAT) and SWAT+ are the most widely used, although their performance
in groundwater-driven watersheds can sometimes be poor due to a simplistic representation
of groundwater processes. The purpose of this paper is to introduce a new physically-based
spatially-distributed groundwater flow module called gwflow for the SWAT+ watershed model. The
module is embedded in the SWAT+ modeling code and is intended to replace the current SWAT+
aquifer module. The model accounts for recharge from SWAT+ Hydrologic Response Units (HRUs),
lateral flow within the aquifer, Evapotranspiration (ET) from shallow groundwater, groundwater
pumping, groundwater–surface water interactions through the streambed, and saturation excess flow.
Groundwater head and groundwater storage are solved throughout the watershed domain using
a water balance equation for each grid cell. The modified SWAT+ modeling code is applied to the
Little River Experimental Watershed (LREW) (327 km2) in southern Georgia, USA for demonstration
purposes. Using the gwflow module for the LREW increased run-time by 20% compared to the
original SWAT+ modeling code. Results from an uncalibrated model are compared against streamflow
discharge and groundwater head time series. Although further calibration is required if the LREW
model is to be used for scenario analysis, results highlight the capabilities of the new SWAT+ code to
simulate both land surface and subsurface hydrological processes and represent the watershed-wide
water balance. Using the modified SWAT+ model can provide physically realistic groundwater flow
gradients, fluxes, and interactions with streams for modeling studies that assess water supply and
conservation practices. This paper also serves as a tutorial on modeling groundwater flow for general
watershed modelers. |
Language: | English |
Keywords: | SWAT+; groundwater; modeling; groundwater–surface water interactions |