By Courtney Swyden
In an effort to predict surface runoff and flooding, a Texas A&M University graduate student and her advising professor are using the SWAT (Soil and Water Assessment Tool) model to simulate runoff on an hourly basis in Texas’ watersheds.
“With the advent of remote sensing technology, radars can not only be used for wireless internet, or traffic ticketing, but they can also be used to track floods on a real-time basis so that we can alert people in advance,” said TAMU graduate student Bakkiyalakshmi Palanisamy.
According to the National Oceanic and Atmospheric Administration, an average of 100 people lose their lives in floods annually in the United States, with flood damage averaging more than $2 billion. The NOAA lists flash floods as the number one weather-related killer in the United States.
The driving force for runoff or soil erosion is rainfall. When the intensity of the rainfall exceeds the infiltration capacity of the soil, surface runoff occurs. Excessive surface runoff results in flooding that can deteriorate land use and land cover, cause soil erosion and damage other natural resources.
“It becomes necessary to predict runoff from a particular area with more accurate, fine resolution inputs such as rainfall estimates from NEXRAD,” said Palanisamy, a recipient of a 2004-05 Texas Water Resources Institute-managed research grant, funded by the U.S. Geological Survey.
NEXRAD, or next generation weather radar, is a system of weather radars that estimates rainfall at a very fine spatial and temporal scale or for relatively small areas.
Palanisamy and her advising professor Dr. Raghavan Srinivasan, director of the Spatial Sciences Laboratory at TAMU, selected the Big Sandy Creek and Walnut Creek watersheds located in the northwest part of the Trinity River basin as her study area. She collected hourly precipitation from the National Climatic Data Center and then used the SWAT model to simulate runoff on an hourly basis. In addition, hourly rainfall estimates from NEXRAD at a spatial resolution of 4km2 were used in generating runoff estimates.
She compared the real-time stream flow measurements obtained from U.S.G.S. to what she obtained from her simulation.
Results indicated that for hydrologic and water quality modeling, rainfall values from a dense rain gauge network should be used in lieu of widely distributed point rain gauge measurements across the study area.
Palanisamy’s research is funded as part of the National Institutes for Water Research annual research program. TWRI is the designated institute for water resources research for Texas.
For more information on Palanisamy’s research, visit “USGS Research Grants” at http://twri.tamu.edu/usgs.php.
