U.S.
GEOLOGICAL SURVEY
Open-File Report 02-250
Fifty-Year Flood-Inundation Maps for Choluteca, Honduras
By D.L. Kresch, M.C. Mastin, and T.D. Olsen
ABSTRACT
After the devastating floods caused by Hurricane Mitch in 1998, maps of the areas and depths of 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 Choluteca that would be inundated by 50-year floods on Río Choluteca and Río Iztoca. Geographic Information System (GIS) coverages of the flood inundation are available on a computer in the municipality of Choluteca 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 50-year-floods on Río Choluteca and Río Iztoca at Choluteca 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.
The estimated 50-year-flood discharge for Río Choluteca at Choluteca is 4,620 cubic meters per second, which is the drainage-area-adjusted weighted-average of two independently estimated 50-year-flood discharges for the gaging station Río Choluteca en Puente Choluteca. One discharge, 4,913 cubic meters per second, was estimated from a frequency analysis of the 17 years of peak discharge record for the gage, and the other, 2,650 cubic meters per second, was estimated from a regression equation that relates the 50-year-flood discharge to drainage area and mean annual precipitation. The weighted-average of the two discharges at the gage is 4,530 cubic meters per second.
The 50-year-flood discharge for the study area reach of Río Choluteca was estimated by multiplying the weighted discharge at the gage by the ratio of the drainage areas upstream from the two locations. The 50-year-flood discharge for Río Iztoca, which was estimated from the regression equation, is 430 cubic meters per second.
Abstract
Introduction
Description of Study Area
Fifty-Year Flood Discharge
Water-Surface Profiles of the 50-Year Flood
Fifty-Year Flood-Inundation Maps
Data Availability
References Cited
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.
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Geographic Information System coverages of flood inundation and flood depth are available at
http://mitchnts1.cr.usgs.gov/projects/floodhazard.html
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Send questions or comments about this report to the author, David L. Kresch (dlkresch@usgs.gov) 253.428.3600 ext. 2683.
For more information about USGS activities in Washington, visit the USGS Washington District home page.
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