Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2007
Publication Date: May 24, 2007
Citation: Gowda, P., Chavez Eguez, J.L., Colaizzi, P.D., Evett, S.R., Howell, T.A., Copeland, K.S. 2007. Two-source energy balance model evaluation for mapping evapotranspiration on the semi-arid Southern High Plains [abstract]. 2007 AGU Joint Assembly, May 22-25, 2007, Acapulco, Mexico. 2007 CDROM. Technical Abstract: Evapotranspiration (ET) is an essential component of the water balance and a major consumptive use of irrigation water and precipitation on cropland. In this study, we applied the Two-Source Energy Balance (T-SEB) model to estimate hourly ET from the Landsat Thematic Mapper (TM) data for the semi-arid Southern High Plains of the United States where more than 90 percent of the groundwater withdrawals are used for irrigation. For this purpose, a Landsat TM image covering a major portion of the Southern High Plains (parts of Texas Panhandle and northeastern New Mexico) was acquired for 23 July 2006 for the overpass at 17:19 GMT. Atmospheric correction on the TM imagery was done using the MODTRAN, an atmospheric radiative transfer model. Comprehensive ground-truth data were collected to develop a detailed land use map showing major crops grown in the region. Performance of the T-SEB was evaluated by comparing mapped ET data with measured hourly ET data on five lysimeters in Bushland, TX [35 deg 11 min N, 102 deg 06 min W; 1,170 m elevation MSL] managed by the USDA-ARS-Conservation and Production Research Laboratory. Lysimeter-measured ET rates varied from 0.24 to 0.71 mm h**1. Comparison of estimated hourly mapped ET values with lysimetric measurements had an accuracy within 6 percent of the measured ET (r**2=0.99), with a root mean square error of 0.03 mm h**-1. These results support the use of T-SEB model for the semi-arid Southern High Plains; however, more evaluation is needed for different agroclimatological conditions in the region.