Location: Soil and Water Management Research
Title: Metric Estimated Et Evaluation on the Semiarid Southern High Plains Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2007
Publication Date: May 22, 2007
Citation: Chavez Eguez, J.L., Gowda, P., Colaizzi, P.D., Evett, S.R., Howell, T.A., Copeland, K.S. 2007. Metric estimated ET evaluation on the semiarid Southern High Plains [abstract]. 2007 AGU Joint Assembly, May 22-25, 2007, Acapulco, Mexico. 2007 CDROM. Technical Abstract: 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, requires efficient agricultural water use. Accurate regional evapotranspiration (ET) maps would provide valuable information on crop water demand and water usage. 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 on 23 July 2006 for the overpass at 17:19 GMT. 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 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 2.4 to 7.0 mm d**-1. A good agreement was found between the remote sensing based ET and measured ET on lysimeters. Comparison of estimated daily mapped ET values with lysimetric measurements had an accuracy within 9% of the measured ET (r**2 = 0.89) with a mean square error of 0.9 mm d**-1. The use of METRIC for estimating ET under advective conditions of the Southern High Plains is promising; however, more evaluation is needed for different agroclimatological conditions.