HR: 17:45h
AN: H54A-06    [Abstracts]
TI: METRIC Estimated ET Evaluation on the Semiarid Southern High Plains
AU: * Chavez, J L
EM: jchavez@cprl.ars.usda.gov
AF: CPRL-USDA-ARS, PO Drawer 10, Bushland, TX 79012, United States
AU: Gowda, P H
EM: pgowda@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: Declining groundwater levels in the Southern High Plains of the United States, and the fact that agriculture in this region uses more than 90% of groundwater withdrawals, combine to increase the demand for efficient agricultural water use. Accurate regional evapotranspiration (ET) maps would provide valuable information on crop water use. In this study, we applied METRIC (Mapping Evapotranspiration at High Resolution using Internalized Calibration), a remote sensing based ET algorithm, and micrometeorological data measured at a grass reference ET weather station maintained by the Texas High Plains Evapotranspiration Network (TXHPET). For this purpose, a Landsat Thematic Mapper image covering a major portion of the Southern High Plains (parts of Texas Panhandle and northeastern New Mexico) was acquired for 23 July 2006 at 11:26 AM CST. Comprehensive ground-truth data were collected to develop a detailed land use map showing major crops grown in the region. Performance of the METRIC model was evaluated using measured 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 2.4 to 7.8 mm/d. Good agreement was found between the remote sensing based ET and measured ET. Comparison of estimated daily mapped ET values with lysimetric measurements had an accuracy within 9% of the measured ET (r2 = 0.89) with a mean square error of 0.9 mm/d. The use of METRIC for advective conditions of the Southern High Plains is promising; however, more evaluation is needed for different agroclimatological conditions.
DE: 1818 Evapotranspiration
DE: 1855 Remote sensing (1640)
SC: Hydrology [H]
MN: 2007 Joint Assembly