Comparison of sap flux, moisture flux tower and MODIS enhanced vegetation index methods for estimating riparian evapotranspiration

By: , and 
Edited by: Christopher M.U Neale and Michael H. Cosh

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Abstract

Riparian evapotranspiration (ET) was measured on a salt cedar (Tamarix spp.) dominated river terrace on the Lower Colorado River from 2007 to 2009 using tissue-heat-balance sap flux sensors at six sites representing very dense, medium dense, and sparse stands of plants. Salt cedar ET varied markedly across sites, and sap flux sensors showed that plants were subject to various degrees of stress, detected as mid-day depression of transpiration and stomatal conductance. Sap flux results were scaled from the leaf level of measurement to the stand level by measuring plant-specific leaf area index and fractional ground cover at each site. Results were compared to Bowen ratio moisture tower data available for three of the sites. Sap flux sensors and flux tower results ranked the sites the same and had similar estimates of ET. A regression equation, relating measured ET of salt cedar and other riparian plants and crops on the Lower Colorado River to the Enhanced Vegetation Index from the MODIS sensor on the Terra satellite and reference crop ET measured at meteorological stations, was able to predict actual ET with an accuracy or uncertainty of about 20%, despite between-site differences for salt cedar. Peak summer salt cedar ET averaged about 6 mm d-1 across sites and methods of measurement.

Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Comparison of sap flux, moisture flux tower and MODIS enhanced vegetation index methods for estimating riparian evapotranspiration
Volume 352
Year Published 2010
Language English
Publisher IAHS Press
Contributing office(s) Southwest Biological Science Center
Description 4 p.
Larger Work Type Conference Paper
Larger Work Title Remote sensing and hydrology
First page 410
Last page 413
Conference Title International Commission on Remote Sensing of IAHS
Conference Location Jacksonhole, Wyoming
Conference Date September 27-30 2010
Online Only (Y/N) N
Additional Online Files (Y/N) N