Page 210 - Biosystems Engineering

188 Cha pte r F i v e

managers and scientists in performing watershed- and basin-scale
studies. AGWA was developed by the USDA-ARS Southwest Water-
shed Research Center, in cooperation with the USEPA Office of
Research and Development Landscape Ecology Branch, to address
four objectives:

1. To provide a simple, direct, and repeatable method for hydro-
logic model parameterization.
2. To use only basic, attainable GIS data.
3. To be compatible with other geospatial watershed–based
environmental analysis software.
4. To be useful for scenario development and alternative futures
simulation work at multiple scales.
AGWA provides functionalities to conduct all phases of a water-
shed assessment for two widely used watershed hydrologic models:
SWAT for large watersheds and long-term simulations, and
KINEROS-2 for small watersheds (<100 km ) for event-based studies
2
(Fig. 5.3). AGWA is designed as a tool for performing relative assess-
ment (change analysis) resulting from land cover/use change. Areas
identified through large-scale assessment with SWAT as being most
susceptible to change can be evaluated in detail at smaller scales with
KINEROS-2. Data used in AGWA include DEMs, land cover grids,
soils data, and precipitation data.
Currently, AGWA is available as AGWA 2.0 for ArcGIS 9.x and
AGWA 1.5 for ArcView 3.x. The interface is similar to USEPA’s BASINS.
There are five major tasks: (1) watershed delineation, (2) land cover
and soils parameterization, (3) writing a precipitation file for model
input, (4) writing parameter files and running the chosen model, and
(5) viewing results.

WMS
WMS is another comprehensive graphical modeling environment for
all phases of watershed hydrology and hydraulics. WMS includes
powerful tools to automate modeling processes. The current version,
WMS 8.1, supports hydrologic modeling with the Hydrologic Engi-
neering Center model HEC-1 (HEC-HMS; HEC-Hydrologic Model-
ing System to simulate surface runoff from a single precipitation
event), TR-20 (to compute surface runoff from natural or synthetic
rainstorm events), TR-55 (simplified method to compute storm
runoff in a small, urbanized watershed), the Rational Method (for
peak discharge), NFF (National Flood Frequency), MODRAT (Modi-
fied Rational Method), and HSPF. Hydraulic models supported
include HEC-RAS (HEC-River Analysis System; one-dimensional
hydraulic model), SMPDBK (Simplified Dam-Break, for predicting
downstream flooding produced by a dam failure), and CE-QUAL-W2