Modelling annual evapotranspiration in a semi-arid, African savanna: functional convergence theory, MODIS LAI and the Penman-Monteith equation

Accurately measuring evapotranspiration (ET) is essential if we are to derive reasonable estimates of production and water use for semi-arid savannas. Estimates of ET are also important in defining the health of an ecosystem and the quantity of water used by the vegetation when preparing a catchment...

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Bibliographic Details
Published in:African journal of range & forage science 2015-01, Vol.32 (1), p.33-39
Main Authors: Palmer, Anthony R, Weideman, Craig, Finca, Andiswa, Everson, Colin S, Hanan, Niall, Ellery, William
Format: Article
Language:English
Subjects:
Convergence
LAI
modelling
plant production
Remote sensing
Theory
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Summary:Accurately measuring evapotranspiration (ET) is essential if we are to derive reasonable estimates of production and water use for semi-arid savannas. Estimates of ET are also important in defining the health of an ecosystem and the quantity of water used by the vegetation when preparing a catchment-scale water balance. We derived ET 0 from an automatic weather station 30 km west of Skukuza, Kruger National Park, South Africa using the Penman- Monteith equation, and then used the MODIS LAI to inform the model of canopy phenological dynamics. This result was compared with 173 days of ET measurements from the eddy covariance (ET ec ) system near Skukuza in 2007 as well as from the ET recorded by a large-aperture scintillometer at the same site in 2005. The model compared favourably with both sets of measured data and, when used independently of the eddy covariance data, ET MODIS predicted an annual ET of 378 mm in 2007 for the semi-arid savanna around the Skukuza flux site.
ISSN:1022-0119
1727-9380
DOI:10.2989/10220119.2014.931305