HR: 1340h
AN: H33A-0969 [WITHDRAWN]    [Abstracts]
TI: A Comparison Between NEXRAD and Rain Gage Interpolation in the Semi-Arid Climate of South Central Texas
AU: * Watts, J L
EM: wattsjl@cdm.com
AF: CDM, 500 President Clinton Avenue Suite RL-10, Little Rock, AR 72201, United States
AB: The forcing data required for a simple hydrologic model are precipitation and evaporation. Traditionally, weather data is acquired from single point gauges and applied using Thiessen polygons over the modeled area. This technique is standard practice, and adequate in a climate with significant frontal weather systems or in a densely gauged area. The Sandies and Elm watershed is located in rural south central Texas. This area is sparsely gauged and has a semiarid climate known for its significant convective storm events. The flow variability of the streams in the Sandies and Elm watershed is defined by these convective storm systems. The hydrologic model needed to be calibrated to these storm events, therefore the storm event data input into the model should accurately represent precipitation with reference to both volume and spatial distribution. Using Geographic Information Systems (GIS), a comparative study between a spatial interpretation of the rain gauge data and NEXRAD (NEXt generation RADar) data was undertaken. The most severe frontal and convective storms were studied for each of the twelve months using a data set from the years 2000 through 2004. The 24- hour precipitation value range and total precipitation were calculated. The 24-hour precipitation spatial images were created for both the rain gauge interpretation and NEXRAD. A comparison of these values and figures were made and verified against the concurrent stream gauge fluctuation. This comparison demonstrated the weakness in gauge interpolation in areas of significant convective storm events. Overall the rain gauges underestimated the precipitation measured by NEXRAD 70% of the time. When the total precipitation was underestimated it was underestimated by an average of 43.2%.
DE: 1819 Geographic Information Systems (GIS)
DE: 1846 Model calibration (3333)
DE: 1848 Monitoring networks
DE: 1853 Precipitation-radar
DE: 1854 Precipitation (3354)
SC: Hydrology [H]
MN: 2007 Fall Meeting