Open-File Report 02-262
Fifty-Year Flood-Inundation Maps for Tocoa, Honduras
By D.L. Kresch, M.C. Mastin, and T.D. Olsen
After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of the 50-year-flood inundation at 15 municipalities in Honduras were prepared as a tool for agencies involved in reconstruction and planning. This report, which is one in a series of 15, presents maps of areas in the municipality of Tocoa that would be inundated by a 50-year flood of Río Tocoa. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Tocoa as part of the Municipal GIS project and on the Internet at the Flood Hazard Mapping Web page (http://mitchnts1.cr.usgs.gov/projects/floodhazard.html). These coverages allow users to view the flood inundation in much more detail than is possible using the maps in this report.
Water-surface elevations for an estimated 50-year-flood on Río Tocoa at Tocoa were estimated using HEC-RAS, a one-dimensional, steady-flow, step-backwater computer program. The channel and floodplain cross sections used in HEC-RAS were developed from an airborne light-detection-and-ranging (LIDAR) topographic survey of the area and a ground survey at one bridge. There are no nearby long-term stream-gaging stations on Río Tocoa; therefore, the 50-year-flood discharge for Río Tocoa, 552 cubic meters per second, was estimated using a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The drainage area and mean annual precipitation estimated for Río Tocoa at Tocoa are 204 square kilometers and 1,987 millimeters, respectively. It was assumed that a portion of the 50-year flood, 200 cubic meters per second, would escape the main channel and flow down a side channel before re-entering the main channel again near the lower end of the study area.
Description of Study Area
Fifty-Year Flood Discharge
Water-Surface Profiles of the 50-Year Flood
Fifty-Year Flood-Inundation Maps
This report and associated figures are available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.
Download the report (PDF, 1.2 MB)
11x17 high resolution versions of Figure
1 (PDF, 4.6 MB)
and Figure 5 (PDF, 1.0 MB) to view or print.
Geographic Information System coverages of flood inundation and flood depth are available at
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Send questions or comments about this report to the author, David L. Kresch (email@example.com) 253.428.3600 ext. 2683.
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Last modified: Wednesday, December 07 2016, 07:04:17 PM