Estimating wide-area evapotranspiration at multiple scales using optical vegetation index methods

Wednesday, 16 December 2015: 08:00
3022 (Moscone West)
Pamela L Nagler1, Edward Glenn2, Chris Jarchow1, Armando Barreto-munoz3, Kamel Didan4, Hamideh Nouri5, Sharolyn Anderson5 and Tanya Doody6, (1)USGS SW Biological Sci Ctr, Tucson, AZ, United States, (2)University of Arizona, Soil, Water, Environmental Sciences, Tucson, AZ, United States, (3)University of Arizona, Electrical and Computer Engineering, Tucson, AZ, United States, (4)University of Arizona, Tucson, AZ, United States, (5)University of South Australia, Adelaide, SA, Australia, (6)CSIRO Land and Water Flagship, Adelaide, Australia
We provide three examples of remotely sensed evapotranspiration (ET) from our research using optical methods at different spatial scales and applied to (i) urban landscapes, (ii) riparian vegetation in Mexico in response to river flows, and (iii) riparian vegetation in Australia in response to different flood frequencies. In the first example, we will compare ground methods for estimating ET by horticultural plants with scaled estimates of ET using both WV2 NDVI imagery and MODIS EVI which were used to determine water requirements of urban gardens in Adelaide, South Australia. In the second example, we will present the impacts of a 2014 environmental flow, released to the Colorado River delta in Mexico, on vegetation greenness and estimated ET using Landsat and MODIS data. Lastly, we will show the results for scaling sap flow transpiration of Red Gum (Eucalyptus camaldulensis) and associated vegetation along the Murrumbidgee River (a tributary of the River Murray) to MODIS-based estimates of evapotranspiration in the wider riparian reaches along the river. These three applications range in spatial scales from a few hectares for urban gardens, to several thousand hectares for the riparian ecosystem in Mexico, to a regional scale of a hundred thousand hectares for the Red Gum forest in Australia. Remote sensing methods can produce accurate estimates of ET across wide temporal and spatial scales, limited mainly by the accuracy of the ground methods by which they are calibrated and validated.