HR: 0800h
AN: H51C-04    [Abstracts]
TI: Two-Source Energy Balance Model Evaluation for Mapping Evapotranspiration on the Semi- arid Southern High Plains
AU: * Gowda, P H
EM: pgowda@cprl.ars.usda.gov
AF: CPRL-USDA-ARS, PO Drawer 10, Bushland, TX 79012, United States
AU: Chavez, J L
EM: jchavez@cprl.ars.usda.gov
AF: CPRL-USDA-ARS, PO Drawer 10, Bushland, TX 79012, United States
AU: Colaizzi, P D
EM: pcolaizzi@cprl.ars.usda.gov
AF: CPRL-USDA-ARS, PO Drawer 10, Bushland, TX 79012, United States
AU: Evett, S R
EM: srevett@cprl.ars.usda.gov
AF: CPRL-USDA-ARS, PO Drawer 10, Bushland, TX 79012, United States
AU: Howell, T A
EM: tahowell@cprl.ars.usda.gov
AF: CPRL-USDA-ARS, PO Drawer 10, Bushland, TX 79012, United States
AU: Copeland, K
EM: kcopeland@cprl.ars.usda.gov
AF: CPRL-USDA-ARS, PO Drawer 10, Bushland, TX 79012, United States
AB: 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 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 11:26 AM CST. Atmospheric correction on the TM imagery was done using 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 model was evaluated by comparing mapped ET data with measured hourly ET data on five weighing lysimeters at Bushland, TX [35 Deg. 11' N, 102 Deg. 06' W; 1,170 m elevation MSL] managed by the Conservation and Production Research Laboratory, USDA-ARS. Lysimeter-measured ET rates varied from 0.24 to 0.71 mm/h. Comparison of estimated hourly mapped ET values with lysimetric measurements had an accuracy within 6% of the measured ET (r2=0.99), with a root mean squared error of 0.03 mm/h. These results support the use of the T-SEB model for the semi-arid Southern High Plains; however, more evaluation is needed for different agroclimatological conditions in the region.
DE: 1818 Evapotranspiration
DE: 1855 Remote sensing (1640)
SC: Hydrology [H]
MN: 2007 Joint Assembly