Vol. 8, No. 2, 140-151, 2009
Abderrahmane Hamimed, Abdelkader Khaldi, Mekki Mehor and Abdelali Seddini
Abstract
The main aim of this study is the use of the
satellite ASTER data for assessing the daily actual evapotranspiration
by solving the energy balance equation at the surface. The energy balance model
used is SEBAL (surface energy balance algorithm for land). It is a one-source
model that calculates the net radiation, soil heat flux and sensible heat flux
at each remote sensing pixel and estimates the latent heat flux as the residual
term in the energy balance. It involves as input the NDVI, surface temperature
and albedo. The study area encompassed by ASTER image
contains extremes in surface albedo, vegetation cover
and surface temperature values. It is located in the Ksar Chellala plains in Algeria.
To estimate the sensible heat flux, which represents the crucial variable in solving the energy balance equation, we opted for a method based on the use of profiles in the surface layer, with the coupling taking place in fluxes at the convective boundary layer base. A simplification of this method by ignoring the atmosphere thermal stability functions can give the same results approximately. It is then possible to estimate the sensible heat flux and calculate the latent heat flux as the residual term of the energy balance. We can then assess the actual daily evapotranspiration and some moisture indices: evaporative fraction, the Priestley and Taylor parameters and the surface resistance to evaporation. These indices allow quantitative monitoring to be done on a pixel basis of the water status degree.
Submitted: 14 Sept 2008
Revised: 15 Nov 2009
Accepted: 16 Nov 2009
Published: 16 Nov 2009
Responsible editor: Rainer Reuter Citation
Hamimed A, A Khaldi, M Mehor & A Seddini, 2009. Estimation of daily actual evapotranspiration in Algerian semiarid environment with satellite ASTER. EARSeL eProceedings, 8(2): 140-151
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EARSeL European Association of Remote Sensing Laboratories, Strasbourg, France |
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BIS-Verlag |