Chapter 4: Application
This implementation study applies traditional methods in hydrologic modeling and compares those traditional processes to those using GIS for three differently sized watershed areas. Four different case studies were performed: (1) measurement from paper maps; (2) on-screen extraction from raster maps; (3) using GIS and two different resolutions of grid-based digital elevation models (DEMs); and (4) using a triangulated irregular network (TIN).
The study areas were determined in a meeting Friday, February 9th, 2001
with David Stolpa of TxDOT. During this meeting Mr. Stolpa mentioned that he
was interested in comparing analyses for certain area sizes, and these watersheds
each met this area size criteria. Buttermilk Creek watershed was chosen initially
as this is an area in which TxDOT has conducted an analysis for a highway
All three study areas are located in Travis County, Texas, as shown in Figure 4.1.