Central and South Central Texas Approximate Floodplain Mapping
For eight days in June to July 2002, a low pressure system pumped moisture from the Gulf of Mexico into central and south central Texas. Rainfall accumulations ranged from 5 to 35 inches across the region, causing nine deaths and damage to thousands of homes. Watershed Concepts was contacted by the Federal Emergency Management Agency to assist in disaster recovery. Watershed Concepts’ role is collecting and surveying high water marks along affected flooding sources and creating Flood Recovery Maps for 15 counties.

Use of Data
The results of these analyses can be downloaded from this web site for use by local communities, contractors, and members of the public at no charge. This data will eventually be used to revise communities’ effective Flood Insurance Rate Maps.

Methodology
The base flood elevations were developed from peak water surface elevations determined through hydrologic analysis. The hydrology was based on regression equations for the Texas region. The hydraulic study utilized 7.5 minute quadrangle map contours to determine cross section geometries and the U.S. Army Corps of Engineers’ step backwater program, HEC-RAS, to compute flood elevations. Since this was an approximate study, no bridge, culvert of dam crossing were taken into account in the analysis.

Data Descriptions

• Flood Recovery Map Panels
• GIS Data
• Engineering Data

High Water Marks Report
Click here for reports on high water marks in PDF format.

Approximate Data by County
County and Waterways Detailed Information