HR: 1330h
AN: H23B-08    [Abstracts]
TI: Evapotranspiration on Western U.S. Rivers Estimated by Remote Sensing and Eddy Covariance Flux Tower Data
AU: * Nagler, P L
EM: pnagler@ag.arizona.edu
AF: University of Arizona, Soil, Water and Environmental Science Dept., Environmental Research Lab (ERL), 2601 East Airport Dr., Tucson, AZ 85706 United States
AU: Russell, S L
EM: rscott@tucson.ars.ag.gov
AF: U.S. Department of Agriculture (USDA) - Agricultural Research Service (ARS); Southwest Watershed Research, Room 101; 2000 E. Allen Rd., Tucson, AZ 85719-1596 United States
AU: Cleverly, J R
EM: cleverly@sevilleta.unm.edu
AF: University of New Mexico, Department of Biology, MSC03 2020, Albuquerque, NM 87131 United States
AU: Westenburg, C
EM: cwesten@usgs.gov
AF: University of New Mexico, Department of Biology, MSC03 2020, Albuquerque, NM 87131 United States
AU: Westenburg, C
EM: cwesten@usgs.gov
AF: U.S. Geological Survey (USGS) - Water Resources Division (WRD), 160 N. Stephanie St., Henderson, NV 89074-8829 United States
AU: Glenn, E P
EM: eglenn@ag.arizona.edu
AF: University of Arizona, Soil, Water and Environmental Science Dept., Environmental Research Lab (ERL), 2601 East Airport Dr., Tucson, AZ 85706 United States
AU: Huete, A R
EM: ahuete@ag.arizona.edu
AF: University of Arizona, Soil, Water and Environmental Science Dept., Terrestrial Biophysics and Remote Sensing (TBRS), 429 Shantz Bldg. #38, Tucson, AZ 85721 United States
AB: Evapotranspiration (ET) rates measured from eight eddy covariance flux towers on three western United States rivers were highly correlated with Enhanced Vegetation Index (EVI) values from Moderate Resolution Imaging Spectrometer sensors on the NASA Terra satellite. Sixteen-day composite values of EVI and maximum daily air temperature (Ta) were combined to predict ET across species and sites (r2 = 0.76). The relationship was then used to estimate ET for 2000-2004 over large river stretches on the Upper San Pedro River, the Middle Rio Grande, and the Lower Colorado River. EVI and ET values were similar across river systems. Measured and estimated ET values tended to be moderate when compared to earlier, and often indirect, estimates, and ranged from 850-1,060 mm yr-1. EVI for individual plant associations, used as a measure of relative ET rates, ranked cottonwood (Populus spp.) and willow (Salix spp.) highest, mesquite (Prosopis glandulosa) and saltcedar (Tamarix ramosissima) intermediate, and giant sacaton (Sporobulus wrightii) and arrowweed (Pluchea sericea) lowest in potential ET. However, saltcedar EVI had a high variance, as this species can grow in sparse to dense stands, depending on water availability. ET rates estimated by remote sensing in this study produced similar values as direct, ground-based measurements on the San Pedro River, but they were much lower than official values estimated for riparian water budgets using crop coefficient methods for the Middle Rio Grande and Lower Colorado River.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1640 Remote sensing
DE: 1655 Water cycles (1836)
DE: 1836 Hydrologic budget (1655)
SC: Hydrology [H]
MN: 2005 Joint Assembly