SWATMOD-PREP: Graphical user interface for preparing coupled SWAT-modflow simulations

Authors: BAILEY, RYAN - Colorado State University; RATHJENS, HENDRIK - Purdue University; BIEGER, KATRIN - Texas Agrilife Extension; CHAUBEY, INDRAJEET - Purdue University; Arnold, Jeffrey

Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2016
Publication Date: 2/3/2017
Publication URL: http://handle.nal.usda.gov/10113/5700694
Citation: Bailey, R., Rathjens, H., Bieger, K., Chaubey, I., Arnold, J.G. 2017. SWATMOD-PREP: Graphical user interface for preparing coupled SWAT-modflow simulations. Journal of the American Water Resources Association. 53(2):400-410. doi:10.1111/1752-1688.12502.

Interpretive Summary: Comprehensive water resource planning requires an understanding of both surface and subsurface processes. For example, pumping irrigation water from an aquifer will directly impact flow from nearby streams. A comprehensive surface/groundwater model is complex and developing input data and displaying output is difficult and time consuming for model users. In a previous study, a surface watershed model was linked with a groundwater flow model and the resulting model was called SWATMOD. In addition, a model for simulating nitrate transport in the groundwater was linked to SWATMOD. In this study, a graphical user interface was developed that couples the surface and groundwater inputs required by the linked SWATMOD into a seamless interface called SWATMOD-Prep. The interface guides the user through importing required maps and data and performs geo-processing operations to develop inputs for the linked model. The use of SWATMOD-Prep is demonstrated for the ARS Little River Experimental Watershed in Tifton, Georgia. The use of SWATMOD-Prep is demonstrated for the Little River Experimental Watershed, Georgia. SWATMOD-Prep and SWAT-MODFLOW executables are available with an accompanying user’s manual at: http://swat.tamu.edu/software/swat-modflow/. The user’s manual also accompanies this paper as Supporting Information. The seamless, comprehensive interface was shown to provide a useful tool for holistic water resource assessment.

Technical Abstract: This paper presents SWATMOD-Prep, a graphical user interface that couples a SWAT watershed model with a MODFLOW groundwater flow model. The interface is based on a recently published SWAT-MODFLOW code that couples the models via mapping schemes. The spatial layout of SWATMOD-Prep guides the user through the process of importing shape files (sub-basins, HRUs, river network) from an existing SWAT model, creating a grid, performing necessary geo-processing operations to link the models, writing out SWAT-MODFLOW files, and running the simulation. The option of creating a new single-layer MODFLOW model for near-surface alluvial aquifers is available, with the user prompted to provide groundwater surface elevation (through a digital elevation model), aquifer thickness, and necessary aquifer parameter values. The option of simulating nitrate transport in the aquifer also is available, using the reactive transport model RT3D. The interface is in the public domain. It is programmed in Python, with various software packages used for geo-processing operations (e.g. selection, intersection of rasters) and inputting/outputting data, and is written for Windows. The use of SWATMOD-Prep is demonstrated for the Little River Experimental Watershed, Georgia. SWATMOD-Prep and SWAT-MODFLOW executables are available with an accompanying user’s manual at: http://swat.tamu.edu/software/swat-modflow/. The user’s manual also accompanies this paper as Supporting Information.