EPA 600/R-19/232 | December 2019 | www.epa.gov/research A Review of Watershed and Water Quality Tools for Nutrient Fate and Transport Office of Research and Development Center for Environmental Solutions & Emergency Response | Groundwater Characterization & Remediation Division EPA 600/R-19/232 December 2019 A Review of Watershed and Water Quality Tools for Nutrient Fate and Transport Tadesse Sinshaw National Research Council Resident Research Associate United States Environmental Protection Agency Robert S. Kerr Environmental Research Center 919 Kerr Research Drive, Ada, OK 74820, USA Lifeng Yuan National Research Council Resident Research Associate United States Environmental Protection Agency Robert S. Kerr Environmental Research Center 919 Kerr Research Drive, Ada, OK 74820, USA Kenneth J. Forshay Project Officer United States Environmental Protection Agency Office of Research and Development Center for Environmental Solutions and Emergency Response Groundwater Characterization and Remediation Division 919 Kerr Research Drive, Ada, OK 74820, USA Office of Research and Development Center for Environmental Solutions & Emergency Response | Groundwater Characterization & Remediation Division Disclaimer This document has been reviewed by the U.S. Environmental Protection Agency, Office of Research and Development, and it has been approved for publication as an EPA document. This technical report presents the result of work directed by Project Officer Kenneth J. Forshay (EPA). The research described in this report has been funded wholly or in part by the U.S. Environmental Protection Agency including support for National Research Council Research Associateship Program Fellows Tadesse Sinshaw and Lifeng Yuan. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. Quality Assurance This work was performed under an EPA-approved quality assurance project plan, “A Review of Tools for Nutrient Fate and Transport Simulation,” (QA ID #: G-GWERD- 0031787-QP-1-1), approved September 24, 2018. Generally, the report contains description and evaluation of existing tools and literature. Primary data collection for this work is limited to publicly available database search results as described in Appendix 1. The data and information used in this document have been assessed by the EPA for this review. Neither the EPA, EPA contractors, nor any other organizations cooperating with the EPA are responsible for inaccuracies in the original data that may be present. Acknowledgements We sincerely thank Dr. Chayan Lahiri for his review and constructive suggestion on revisions of this report. We also express gratitude to other reviewers of this report, including Dr. Jessica Brumley, Dr. David Burden, and Pat Bush. Dr. Tadesse Sinshaw and Dr. Lifeng Yuan appreciate support from the NRC Research Associateship award funded by the U.S. EPA while in residency at the U.S. EPA’s Robert S. Kerr Environmental Research Center, Ada, OK 74820. This work is part of the Office of Research and Development, Safe and Sustainable Water Resources National Program, Project No. SSWR 3.01d. ii Contents Acronyms ....................................................................................................................................iv 1.0 Introduction ...........................................................................................................................1 1.1 Purpose of the Report .....................................................................................................1 1.2 Organizational Framework ..............................................................................................1 2.0 Background ............................................................................................................................2 2.1 Overview of Water Quality Management .......................................................................2 2.2 Roles of Models in Water Quality Management .............................................................2 3.0 Models for Nutrient Fate and Transport ................................................................................4 3.1 Watershed Loading Models .............................................................................................5 3.2 Mixing Models ...............................................................................................................24 3.3 Surface Water Quality Models .......................................................................................28 3.4 Groundwater Quality Models ........................................................................................36 4.0 Findings from Past Applications ..........................................................................................42 4.1 Watershed Loading Models ...........................................................................................42 4.2 Mixing Models ...............................................................................................................44 4.3 Surface Water Quality Models .......................................................................................46 4.4 Groundwater Quality Models ........................................................................................48 5.0 Recommended Strategy for Model Selection ......................................................................50 6.0 Conclusions .........................................................................................................................57 References .................................................................................................................................58 Appendix 1: Model Search Strategy ........................................................................................ A1 iii Acronyms AGNPS Agricultural NonPoint Source Pollution NCCHE National Center for Computational Model Hydroscience and Engineering AGWA Automated Geospatial Watershed NH4 Ammonium Assessment Tool NO2 Nitrite AnnAGNPS Annualized Agricultural NonPoint Source Pollution Model NO3 Nitrate BASINS Better Assessment Science Integrating NOAA National Oceanic and Atmospheric Point and Nonpoint Sources Administration BMPs Best Management Practices NPS NonPoint Source BOD Biological Oxygen Demand N-SPECT NonPoint Source Pollution and Erosion CAT Climate Assessment Tool Comparison Tool CEAM Center Exposure Assessment Models OpenNSPECT Open NonPoint Source Pollution and Erosion Comparison Tool CORMIX Cornell Mixing Zone Expert System P Phosphorus CWA Clean Water Act PLOAD Pollutant Loading Estimator DEM Digital Elevation Model PO4 Phosphate DO Dissolved Oxygen RHEM Rangeland Hydrology and Erosion Model DOC Dissolved Organic Carbon RUSLE Revised Universal Soil Loss Equation EAAMOD Everglades Agricultural Area Model SCS-CN Soil Conservation Service Curve Number ECM Export Coefficient Model SLAMM Source Loading and Management Model EFDC Environmental Fluid Dynamics Code SUTRA Saturated-Unsaturated Transport EMC Event Mean Concentration SWAT Soil and Water Assessment Tool EPA Environmental Protection Agency SWET Soil and Water Engineering Technology, GenScn GENeration and Analysis of Model Inc. Simulation SCeNarios SWMM Stormwater Management Model GEPD Georgia Environmental Protection Division TKN Total Kjeldahl Nitrogen GIS Geographic Information System TMDL Total Maximum Daily Load GLEAMS Groundwater Loading Effects of Agricultural Management Systems TN Total Nitrogen GWLF Generalized Watershed Loading Function TP Total Phosphorus HEC-RAS Hydrologic Engineering Center’s River TSS Total Suspended Solids Analysis System USACE United States Army Corps of Engineers HRU Hydrologic Response Units USDA-ARS United States Department of Agriculture - HSPF Hydrologic Simulation Program - Fortran Agricultural Research Service HST3D Heat- and Solute-Transport Program USGS United States Geological Survey HUSLE Hydro-geomorphic Universal Soil Loss USLE Universal Soil Loss Equation Equation VP Visual Plume KINEROS2 Kinematic Runoff and Erosion 2 WAM Watershed Assessment Model LID Low Impact Development WARMF Watershed Analysis Risk Management LSPC Loading Simulation Program Frame L-THIA The Long-Term Hydrologic Impact WASP Water Quality Analysis Simulation Program Assessment WDMUtil Watershed Data Management Utility MUSLE Modified Universal Soil Loss Equation WMS Watershed Modeling System N Nitrogen WQM Water Quality Management iv 1.0 Introduction 1.1 Purpose of the Report The purpose of this report is to provide an overview of common watershed and water quality tools and models that are used to estimate water quality, nutrient fate and transport, and non-point source (NPS) pollution. Watershed and water quality management activities are supported by various tools. Tools integrate multiple approaches and techniques to describe a watershed system and its natural processes. A tool can be a method, technique, data- base, or model that is used to study a watershed system. Many watershed and water quality models have been developed to help improve our understanding of watershed processes. These models simplify complex physical processes through mathematical, empirical or statistical relationships and construct the conceptual framework of primary physical processes to represent natural processes that exist in a watershed. Watershed and water quality models help watershed managers generate useful information that assists in environmental decision making. The core of some tools is a mathematical model that represent an