Model Library

ound-Water Flow Model - Reactive Transport in 3-Dimensions (SWAT-MODFLOW-RT3D)

Model name: Soil and Water Assessment Tool - Modular Ground-Water Flow Model - Reactive Transport in 3-Dimensions (SWAT-MODFLOW-RT3D)

Developed by: Dr. Ryan Bailey and Dr. Tyler Wible (Last update: 2016)

Model type: Quasi-dynamic, semi-distributed, deterministic, process-based, ecohydrological small watershed to river basin-scale model

History: The model combines the land surface and stream hydrologic processes of SWAT and the groundwater hydrologic processes of MODFLOW, and transport of contaminants of RT3D model.

Computational requirements: 32-bit and 64-bit Windows/Linux, Intel FORTRAN Compiler for Microsoft Visual Studio 10.

Software requirements: GIS (required): QSWAT-MOD

Link to download model:

  • Note: RT3D is embedded as a routine of MODFLOW in SWAT-MODFLOW.

Capabilities and Limitations:

Capabilities

  • The SWAT-MODFLOW-RT3D model is a valuable tool for understanding how nitrate moves through surface and subsurface systems. (Wei et al., 2019);
  • It supports the development of practical strategies to reduce pollution in agricultural watersheds (Wei et al., 2019);
  • The model considers spatial-temporal distribution and allows for realistic long-term distribution of nutrient sources based on current land use practices (Wei et al., 2019);
  • It produces maps of groundwater nutrient concentrations and fluxes, helping pinpoint hot spots in aquifers and areas where nutrients are entering rivers (Wei et al., 2019).

Limitations

  • Currently (Dec 2019), the model does not account for NO3 transport in the vadose zone (Wei et al., 2019);
  • It requires so many parameters related to the water quality, runoff and water level (Zhang et al., 2024);
  • It inherits limitations of SWAT model in simulating flood events (Zhang et al., 2024).

Model Inputs and Outputs:

Inputs

Topography data, LULC data, Soil data, Meteorological data, Hydrological data, Water quality data, Management data, Hydrogeological data, Initial and Boundary Conditions, Groundwater Recharge Data, Reaction Parameters, Transport Parameters

Outputs

  • The model simulates surface runoff, soil lateral flow, groundwater storage, and exchange rates, along with nutrient loads, salt ion concentrations in soil and groundwater, and crop yield affected by salinity (Wei et al., 2019).
  • It also tracks salt ion fluxes across various processes, including runoff, recharge, discharge, irrigation, precipitation, and dissolution (Wei et al., 2019).

Examples:

References

Yifru, B. A., Chung, I. M., Kim, M. G., et al. (2022). Assessing the effect of urbanization on regional-scale surface water-groundwater interaction and nitrate transport. Scientific Reports, 12, 12520. https://doi.org/10.1038/s41598-022-16134-1

Rafiei, V., & Nejadhashemi, A. P. (2023). Watershed scale PFAS fate and transport model for source identification and management implications. Water Research, 240, 120073. https://doi.org/10.1016/j.watres.2023.120073

Objectives

The objective of the study was to model the effect of urbanization, particularly in the developing world, on regional-scale surface water-groundwater interactions (SGI) and nitrate loading using an integrated SWAT-MODFLOW-RT3D model.

The objectives of the study were: 1) Quantification of PFOS mass fluxes transported by surface runoff, lateral flow, and sediment as well as PFAS leaching to the GW; 2) Identification of the primary factors influencing PFOS fate and transport from contaminated sources, urban areas, and agricultural fields that can be used for strategic monitoring and remediation planning at large scale.

Other resources: SWAT-MODFLOW-RT3D-WET model’s source code