Watershed Analysis Risk Management Framework (WARMF)

SOFTWARE REVIEW by John E. McCray

The Watershed Analysis Risk Management Framework (WARMF), developed by Systech Engineering Inc., is a numerical model used to simulate watershed hydrology and pollutant transport, and to develop TMDLs. It has been used for problems in many watersheds in the U.S. and several in Asia. The focus of model output is to provide information on water quality of streams, tributaries, and lakes given many different non-point and point sources of pollution. The numerical watershed consists of sub-watersheds, each with a stream segment. WARMF rigorously simulates hydrology, including precipitation, evapotranspiration, infiltration, runoff, stream flow and routing, lake mixing and stratification; and groundwater flow. Pollutant transport applications have included acid mine drainage; inputs from septic systems; bacterial pollution; dissolved oxygen; mercury loading and transport; sediment transport; periphyton in rivers; and algae in stratified reservoirs. It has been used to develop, calculate, and assess Total Maximum Daily Loads (TMDLs) to meet water quality criteria for designated uses. Input data is readily obtained from NOAA, EPA, and USGS sources. However, WARMF is more than just a watershed hydrology model. It also includes software to help stakeholders develop and evaluate water-quality management alternatives for a river basin. The software guides user's through a series of steps designed to help them understand their watershed and the relative impacts of various pollutant sources, with a goal to assist regulators and stakeholders make informed decisions.

WARMF is organized into 5 linked modules under one, GIS-based graphical user interface (GUI). The Engineering module is the dynamic, simulation model that drives WARMF. The Data module provides time series input data (meteorological, point source) and calibration data. The Knowledge module is a utility to store important documents for the watershed. At the center of WARMF are the two watershed approach modules for Consensus building and TMDL calculation. These two modules are roadmaps that provide guidance for stakeholders during the decision making process. WARMF operates on a PC platform in its own GIS environment.


 

An important advantage of WARMF is that it has been designed to look at non-agricultural, as well as agricultural problems. The applications for acid mine drainage, mercury pollution, and on-site wastewater systems would be very difficult to implement in most agricultural-based watershed models. For example, WARMF can allow liquid septic tank effluents to be released below the ground surface with specified composition. Most agricultural based models would require simulating the inputs as applied with irrigation or as fertilizer. Some aspects of the formulation are more satisfying from a physical standpoint. For example, it uses physically based algorithms that track the mass balance and geochemistry through the soil layers rather than using specified soil concentrations, and it simulates hydrology using a dynamic water balance based on the physical processes of snow, soils, and surface hydrology rather than empirical methods (e.g., SCS runoff method). This formulation results in fewer input parameters that are more intuitive than for most models. While models with more input parameters make calibration easier (more knobs to tweak), they often produce in non-unique parameter combinations. Such models often have relatively more difficulty predicting hydrologic data beyond the calibration period. Finally, the WARMF GUI is much more user-friendly than most other watershed models with a similarly comprehensive formulation. Once set up, WARMF is a stand alone tool that can be easily distributed to stakeholders who may not have access to ArcView.


Overall, WARMF is an excellent watershed model. A few weaknesses exist. Like most watershed models, WARMF does not rigorously simulate ground-water processes. It models up to 4 soil layers in the shallow ground water zone. In this region, it accounts for the exchange between the surface water and the unsaturated zone. It does not model deep groundwater aquifers. For example, all sub-watersheds are assumed to be closed, storage effects are not considered, and deep ground-water quality is not tracked. In the TMDL module, percent reductions can be specified for either point or nonpoint source and WARMF will calculate the other. However, as the TMDL module runs through its iterations, it will reduce all upstream sources using the same percent reduction. For example, if multiple point sources exist within a sub-watershed or upstream, all nonpoint sources are reduced by equal percentages; the model can not account for individual source contributions. The allocation of the individual point source reductions is then left to be determined by the stakeholders in the watershed.


WARMF may be downloaded EPA Ecosystem Research Division TMDL Modeling Toolbox (http://www.epa.gov/athens/wwqtsc/ ) at no cost. WARMF is compatible with EPA BASINS 3.1, which is also free. BASINS can be used for model set up and then WARMF is a stand alone tool. A WARMF user can use BASINS to extract data (meteorology, land use, stream gaging, water quality, etc.), set up a watershed delineation, and generate necessary GIS input files to set up a WARMF application. Then using WARMF, a user can import GIS layers for catchment boundaries, river networks, reservoir locations, land use, etc. WARMF will link these entities together to create the watershed network. Then a user can proceed with additional data importing and model calibration. Technical support can be contracted through the developer. There is also a WARMF user's group list server where WARMF user's can ask questions and share information ( http://www.systechengineering.com/WARMFTechSupport.htm ) A series of WARMF training workshops will be hosted by EPA in 2006. Please check EPA Ecosystem Research Division's websites for details in the near future.


Rating System
5=Excellent, 4=Very Good, 3=Good, 2=Satisfactory, 1=Poor

Ease of Use
3
GUI
5
Application

Watershed Water Quality and Hydrology

Output/Plotting
5
Documentation
4
Best Feature
TMDL Tool
Speed
3
Worst Feature
Ground Water Simulation
Overall Rating
4