GEOSPATIAL DATABASE AND PRELIMINARY
FLOOD HYDROLOGY MODEL FOR THE LOWER COLORADO BASIN
by Sarah Anne Stone, B.S.
ABSTRACT
A detailed methodology is presented for using a variety of standard
and
specialized data sources to construct a comprehensive geodatabase
for the Lower
Colorado River basin in Texas and create a preliminary flood hydrology
model
from the geodatabase. A stream network is prepared in a GIS environment
from
the National Hydrography Dataset, creeks data produced by the Capital
Area
Planning Council and the City of Austin, and digitizations based
on the USGS
Digital Orthophoto Quarter-Quadrangles and USGS Digital Raster Graphics
Quadrangles. A measure system is implemented along the reaches.
The National
Elevation Dataset is used together with the streams to delineate
watersheds with
the procedure used by CRWR-PrePro. Watershed outlets come from stream
confluences, intersections of USGS hydrologic cataloging units with
streams,
bridges in the Texas Department of Transportation county roads coverages,
LCRA gage locations, and points selected specifically for the shapes
and sizes of
watersheds they produce. Parameters for hydrologic modeling are
determined for
each of the watersheds from the National Land Cover Dataset, a Lower
Colorado
River Authority land cover dataset, STATSGO soils data, and the
streams and
watershed topology. The parameters are transferred to an HEC-HMS
basin file
for which calibration and use for hydrologic modeling in conjunction
with
hydraulic modeling for flood analysis is planned.
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but please credit the authors and the Center for Research in Water
Resources, The University of Texas at Austin. All commercial rights
reserved. Copyright 1997 Center for Research in Water Resources.
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