CU-Boulder Researchers Map Texas Floods To Support Forecasting And Relief Efforts

June 22, 2007

Researchers from the University of Colorado at Boulder's Center for Environmental Technology used one of their airborne remote sensing instruments to help map the extent of recent flooding in north Texas and support forecasting and relief efforts.

The group, headed by Professor Al Gasiewski, had been operating a Polarimetric Scanning Radiometer, or PSR, on the NASA P-3 aircraft as part of the Cloud and Land Surface Interaction Campaign, or CLASIC, experiment. CLASIC is organized by the U.S. Department of Energy's Atmospheric Radiation Measurement program, and researchers used the CU-Boulder instrument as part of an experimental campaign to map soil moisture over Oklahoma.

The recent weather over Oklahoma and Texas has been exceptionally wet, however, and flooding has been almost a daily occurrence in the northern parts of both states. Persistent thunderstorms inundated parts of the Red River floodplain around Gainesville, Texas, from June 18 to June 20, causing loss of life and significant flood damage.

The CU-Boulder group and P-3 crew from NASA Wallops Flight Facility in Virginia were able to modify their experiment plans to fly over the Red River area and provide the first-ever maps of soil moisture and flooded areas to help support forecasting and relief efforts. The maps were produced in near-real time as a result of recent efforts in remote-sensing instrument software research and development being carried out within the CU-Boulder electrical and computer engineering department.

CU-Boulder researcher Marian Klein and undergraduate student Eric McIntyre were responsible for operating the PSR and produced the maps shortly after the NASA aircraft landed. Thomas Jackson of the U.S. Department of Agriculture collaborated on the project.

Based in the CU-Boulder College of Engineering and Applied Science, the Center for Environmental Technology has developed a cadre of advanced environmental sensing equipment for use on ships, manned and unmanned aircraft, spacecraft and ground-based platforms in extreme environments like the Arctic.

The PSR, which has logged more than 800 hours of flight time in the last decade on various types of aircraft, has extremely sensitive microwave receivers that produce high-resolution images of Earth's oceans, land, ice, clouds, snowpack and precipitation. The images are used to develop better weather and climate models, which lead to improved forecasting abilities, said Gasiewski.

"The opportunity to use the PSR to map flooded land arose as the result of near unprecedented rainfall during the CLASIC experiment along with exceptional readiness on the part of the CU research team and NASA crew," he said.

According to the National Weather Service, flooding produces more fatalities in the United States than any other single meteorological event other than extreme heat, with an average of 84 deaths per year from 1995 to 2004. Although this number has decreased somewhat in recent years, the amount of flood-related damage continues to climb, even after adjusting for inflation.

Weather forecasters currently rely on rainfall-runoff models to determine how much rainfall is required to cause small-scale flooding. These models rely on soil wetness information, which currently is supplied by other models to determine the ability of the soil to absorb rainfall.

While models continue to improve, they cannot always provide a reliable measure of the capacity of soil to absorb rainfall, said Gasiewski. The CU-Boulder sensor provides a new means of determining the capacity by remote measurement.

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