CRWR Online Report 2001-4

 
 

Geospatial Database and Preliminary Flood Hydrology Model for the Lower Colorado Basin

By Sarah Anne Stone, David R. Maidment, and Francisco Olivera

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.

CRWR Online Report 2001-4

 

Geospatial Database and Preliminary Flood Hydrology Model for the Lower Colorado Basin

By By Sarah Anne Stone, David R. Maidment, and Francisco Olivera

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