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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #377318

Research Project: Resilient Management Systems and Decision Support Tools to Optimize Agricultural Production and Watershed Responses from Field to National Scale

Location: Grassland Soil and Water Research Laboratory

Title: Enhancing SWAT+ simulation of groundwater flow and groundwater-surface water interactions using MODFLOW routines

item BAILEY, RYAN - Colorado State University
item PARK, SEONGGYU - Texas Agrilife Research
item BIEGER, KATRIN - Texas Agrilife Research
item Arnold, Jeffrey
item ALLEN, PETER - Baylor University

Submitted to: Journal of Environmental Modeling and Software
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2020
Publication Date: 2/15/2020
Publication URL:
Citation: Bailey, R.T., Park, S., Bieger, K., Arnold, J.G., Allen, P.M. 2020. Enhancing SWAT+ simulation of groundwater flow and groundwater-surface water interactions using MODFLOW routines. Environmental Modelling and Software. 126:104660.

Interpretive Summary: The Soil and Water Assessment Tool (SWAT+) is currently being used in two national modeling efforts to determine the environmental impacts of USDA conservation policy and to develop new policy alternatives: 1) the Conservation Effects Assessment Project and 2) the Long Term Agroecosystems Research project. However, the groundwater flow module in SWAT+ is not physically based and cannot simulate all the scenarios needed for national conservation assessments. In this study, SWAT+ is linked with a physically based groundwater flow model, MODFLOW, to simulate groundwater and surface water interactions more accurately within a watershed system. The linked model was applied and validated for the Middle Bosque River Watershed in central Texas. With the linked SWAT+/MODFLOW system, future USDA conservation assessments will be capable of simulating spatially detailed groundwater scenarios including: 1) effects of irrigation withdrawals on stream flow, 2) low river flows for ecological assessment, 3) sustainability of aquifers, and 4) conjunctive use of surface and groundwater resources.

Technical Abstract: This paper presents a version of SWAT+ that uses MODFLOW to simulate groundwater flow and groundwatersurface interactions within a watershed system. The modeling code is applied to the 470 km2 Middle Bosque River Watershed (Texas, USA) to demonstrate accuracy and differences with SWAT+. The model is tested against field-measured stream discharge, groundwater levels and fluctuation patterns, runoff, baseflow, recharge, watershed boundary groundwater flow, groundwater-surface water interactions, and evapotranspiration. The model captures the dominant baseflow patterns throughout the watershed and the key patterns of water table dynamics and relation to nearby streams. Whereas annual rates of runoff, lateral flow, and annual percolation are unchanged from a stand-alone SWAT+ simulation, annual groundwater discharge rates increase by 50% (37 mm–54 mm). In particular, temporal patterns of groundwater discharge are governed by the physically-based rise and fall of groundwater near streams, rather than storm-induced recharge pulses as in the SWAT+ simulation.