CRWR Online Report 99-4

Geospatial Data in Water Availability Modeling

By Bradley Taylor Hudgens, MSE and David R. Maidment

ABSTRACT

A method is presented for determining flow distribution parameters of drainage area, curve number, and mean annual precipitation from geospatial data sets.  The parameters are used to distribute naturalized streamflows from gaged sites to ungaged sites in a water availability model.  The method is illustrated by application to the Sulphur River basin in Northeast Texas.  Two scales of digital elevation data, 1:250,000 and 1:24,000, are used to automatically delineate watersheds for selected points in the basin.  A digital stream network is built by adding manually digitized tributaries from 1:24,000 scale topographic maps to an existing 1:100,000 scale stream coverage.  The stream network is used to modify the digital elevation data to better reflect mapped hydrography.  Watersheds defined by the 1:24,000 scale elevation data are observed to accurately reflect the land surface shown on a 1:24,000 scale topographic map.  Curve number and precipitation parameters for these watersheds are extracted from existing geospatial data sources.