Vol. 8, No. 2, 140-151, 2009

Estimation of daily actual evapotranspiration in Algerian semiarid environment with satellite ASTER
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.

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History
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 Library and Information System, Carl von Ossietzky University of Oldenburg

 

ISSN 1729-3782