AGWA is the product of a
cooperative effort by the following:

USDA

United States
Environmental Protection
Agency

THE UNIVERSITY

of Arizona

EPA/600/C-06/001
ARS/137460

EPA/600/C-07/Q15
ARS/218468

EPA/600/C-13/148
ARS/296053

Additional information on AGWA is
available on our websites:

http: / / www.tucson.ars.ag.gov/agwa/
http: / / www.epa.gov/esd/land-sci/agwa/

For more information, please contact:

David Goodrich

USDA-ARS SWRC
2000 E. Allen Rd.

Tucson, AZ 85719
Phone: 520-647-9241
Fax: 520-670-5550

Shea Burns

USDA-ARS SWRC
2000 E. Allen Rd.

Tucson, AZ 85719
Phone: 520-647-9328
Fax: 520-670-5550

William Kepner

EPA/ORD
P.O. Box 93478
Las Vegas, NY 89193
Phone: 702-798-2193
Fax: 702-798-2692

The Automated
Geospatial Watershed
Assessment Tool

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US. BPA
Office of Research & Development

Las Vegas, Nevada


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What is AGWA?

The Automated Geospatial Watershed Assessment (AGWA) tool is a GIS-based multipurpose hydrologic analysis system
for use by watershed, water resource, land use, and biological resource managers and scientists in performing watershed-
and basin-scale studies. It uses readily available spatial data sets to parameterize and run two widely used watershed runoff
and erosion models. AGWA is designed to support landscape assessment at multiple spatial and temporal scales. AGWA is
currently available as AGWA 1.5 for Environmental Systems Research Institute (ESRI) Arc View 3.x GIS software, AGWA
2.x for ESRI ArcGIS 9.x, and AGWA 3.X for ESRI ArcGlS 10.x.

Delineation and Discretization

The watershed is delineated from a DEM based on an
outlet selected by the user or a known gage location.
The watershed is then discretized according to the
model type and a user-defined contributing source
area.

Rainfall

Both models can handle distributed rainfall input —
KINEROS interpolates a rainfall surface, and rainfall
depths for SWAT watershed elements are computed in
AGWA using the Thiessen polygon method. Uniform
rainfall (single gage), or design storm (KINEROS only)
data can also be used.

Land Cover and Soils Parameterization

Watershed elements are intersected with soil and land
cover data layers to extract requisite hydrologic
properties.

Visualization

Results from model simulations can be displayed
visually for both watershed elements and channels. All
reported components of the water budget for each
model can be viewed.

Watershed model
descriptions

KINEROS

The kinematic runoff and erosion model
KINEROS is an event oriented, physically based
model developed at the USDA-ARS to describe die
processes of interception, infiltration, surface
runoff and erosion from small agricultural and
urban watersheds. The watershed is represented by
a cascade of planes and channels; the partial
differential equations describing overland flow,
channel flow, erosion and sediment transport are
solved by finite difference techniques. The spatial
variation of rainfall, infiltration, runoff, and erosion
parameters can be accommodated. KINEROS may
be used to determine the effects of various artificial
features such as urban developments, small
detention reservoirs, or lined channels on flood
hydrographs and sediment yield.

SWAT

The Soil and Water Assessment Tool (SWAT) is a
distributed, lumped-parameter model developed at
the 13SDA-ARS to predict the impact of land
management practices on water, sediment and
agricultural chemical yields in large (basin scale)
complex watersheds with varying soils, land use and
management conditions over long periods of time
(> 1 year). SWAT is a continuous-time model, i.e. a
long-term yield model, using daily average input
values, and is not designed to simulate detailed,
single-event flood routing. Major components of
the model include: hydrology, weather generator,
sedimentation, soil temperature, crop growth,
nutrients, pesticides, groundwater and lateral flow,
and agricultural management. The Curve Number
method is used to compute rainfall excess, and flow
is routed through the channels using a variable
storage coefficient method.


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