EPA/600/C-13/148
ARS/296053
The Automated Geospatial
Watershed Assessment Tool Version 3.0
Planning and assessment in land and water resource management are evolving from simple, local-scale problems toward
complex, spatially-explicit, regional ones. Such problems have to be addressed with distributed models that can compute
runoff and erosion at different spatial and temporal scales. The extensive data requirements and the difficult task of
building input parameter files, however, have long represented an obstacle to the timely and cost-effective use of such
complex models by resource managers.
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EPA/600/C-13/148
ARS/296053
t practices on water, sediment and agricultural chemical yields in large, complex watersheds with varying soils, land use and
management conditions over long periods of time (> 1 year). SWAT is a continuous-simulation model, i.e. a long-term yield
model, using daily average input values, and is not designed to simulate detailed, single-event flood routing. For more
information on SWAT, please visit www.brc.tamus.edu/swat.
AGWA DESCRIPTION AND USES
Using digital data in combination with the automated functionality of
AGWA greatly reduces the time required to use these two watershed
models. Through a robust and intuitive interface the user selects an
outlet from which AGWA delineates and discretizes the watershed using
Digital Elevation Model (DEM) information. The watershed elements are
then intersected with soil, land-use/cover, and precipitation (uniform or
distributed) data layers to derive the requisite model input parameters.
The model is then run, and the results are imported back into AGWA for
visual display.
Model outputs that can be displayed in AGWA are shown in the table to
the right. This feature allows managers to identify problem areas for
further monitoring and management activities. Additional functionality
can generate alternative future land-use/cover scenarios and display
differences between simulation outputs (potential change), designed to
provide decision support when combined with planning efforts.
AGWA is designed to provide qualitative estimates of runoff and erosion
relative to landscape change. It cannot provide reliable quantitative
estimates of runoff and erosion without careful calibration. It is also
subject to the assumptions and limitations of its component models.
Digital Elrvirloa Model
Output variables that can be displayed in AGWA.
AVAILABILITY
There are currently several versions of AGWA available: AGWA 1.5
for Environmental Systems Research Institute (ESRI) ArcView 3.x,
AGWA 2.x for ESRI ArcGIS 9.x, and AGWA 3.X for ESRI ArcGIS 10.x. In
addition to ArcView 3.x, ArcGIS 9.x, or ArcGIS 10.x, AGWA requires
the Spatial Analyst extension corresponding to the respective
software platform.
KINEROS
SWAT
Infiltration (mm, m /km)
Infiltration (in, ac-ft/mi)
Runoff (mm, m3)
Peak flow (m3/s, mm/hr)
Sediment yield (kg/ha)
Channel scour (mm/m2)
Sediment discharge (kg/s)
Erosion (depth/area)
Precipitation (mm)
ET(mm)
Percolation (mm)
Surface runoff (mm)
Transmission loss (mm)
Sediment Yield (t/ha)
Water Yield (mm)
Nitrate (kg N/ha)
Phosphorous (kg P/ha)
FOR FURTHER INFORMATION CONTACT:
David C. Goodrich or Shea Burns
USDA-ARS Southwest Watershed Research Center
2000 East Allen Road
Tucson, AZ 85719-1596
http://www.tucson.ars.ag.gov/agwa
USDA
William G. Kepner
U.S. Environmental Protection Agency
P.O. Box 93478
Las Vegas, NV 89193-3478
http://www.epa.gov/nerlesdl/land-sci/agwa/index.htm
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