USGS Washington Water Science Center
|U.S. Department of the Interior
U.S. Geological Survey
Release: May 9, 2002
253-428-3600, ext. 2609
After years of hard work, the Central American country of Honduras is still recovering from the devastation of Hurricane Mitch. Flood-mapping techniques developed by the U.S. Geological Survey (USGS), in cooperation with the U.S. Agency for International Development (USAID), will help the recovery by providing reliable, accurate maps of flood hazard areas to guide rebuilding efforts. The techniques and their application to Honduras are described in a report released today by the USGS.
In October 1998, Hurricane Mitch, a category-5 hurricane listed as the deadliest in the Western Hemisphere since 1780, made landfall on the Honduran coast and spent four days dumping record rainfall, resulting in severe flooding. In Honduras, the storm caused 7,000 deaths, destroyed 33,000 homes and 95 bridges, and damaged 70 percent of the roads.
Shortly after Mitch hit, the USGS sent personnel to assess the damage and begin a series of scientific studies to help with the reconstruction. USAID provided funding for the studies that included a rapid mapping of flood-prone areas in order to guide rebuilding efforts already underway. With these maps, safer places to build new houses, bridges and roads could be located.
To generate the maps as quickly as possible, USGS hydrologists turned to a high-tech airborne laser terrain mapping system.
"A laser fixed to an airplane with a precision global positioning system (GPS) was flown over the river valleys," said USGS hydrologist Mark Mastin. "The system collected ground surface elevation data at a rate of 25,000 data points per second with amazing accuracy.
"One of the challenges of the project was how to handle and store the vast amounts data that this new technology produces."
The data collected by the airborne laser system was fed into a computer that, using an hydraulics computer program, quickly produced a map of "50-year-flood" areas and the likely depths of water.
This new way of quickly getting accurate elevation data by using airborne lasers, called LIDAR, has only recently seen use in the United States. "We wanted to advance the science as much as was practical in a region that desperately needed the information quickly," said Mastin. "Lessons learned in the Honduras project will also certainly help our applications in the United States."
The report, "Flood-Hazard Mapping in Honduras in Response to Hurricane Mitch, " by Mark C. Mastin, is published as U.S. Geological Survey Water-Resources Investigations Report 01-4277. Copies of the report are available for reading at the U.S. Geological Survey, 1201 Pacific Avenue, Suite 600, Tacoma, WA 98402. Copies can be purchased from the U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225-0286, telephone 303-202-4200.
The USGS, a bureau within the Department of the Interior, serves the nation by providing reliable scientific information to describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect our quality of life.
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