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Universiti Teknologi Malaysia (2009)

Estimation of regional evapotranspiration using remote sensing data in arid areas

Abdullah Almhab, Ayoub Ahmed

Titre : Estimation of regional evapotranspiration using remote sensing data in arid areas

Auteur : Abdullah Almhab, Ayoub Ahmed

Université de soutenance : Universiti Teknologi Malaysia

Grade : Doctor of Philosophy (Remote Sensing) 2009

Evapotranspiration (ET) constitutes a large portion of the hydrologic cycle and considered as the important parameter in the water budget in the arid areas. Measurement of the water vapour cycle of the land surface is crucial in improving the management of the limited fresh water resources. This study investigates the possibilities of generating a new algorithm for estimating ET in the arid mountainous areas. The modified SEBAL (Surface Energy Balance Algorithm for Land) was developed based on original SEBAL algorithm produced by Bastiaanssen in 1995. A new modified SEBAL is developed to compute ET in three areas. Operational modified SEBAL model estimates ET of mountain areas of Sana’a basin in Yemen using Remote Sensing data from various sensors and appropriate meteorological data. Validation of ET calculated by modified SEBAL model at a local scale was performed by comparing it with several ET estimated using other methods. Generated in this study are, almost all of the model parameters which covers : surface albedo estimation, estimated Leaf area index (LAI) by remote sensing data analyses, effect of elevation on surface temperature, ground heat flux estimation, impact of surface roughness, the estimated of sensible heat flux, windspeed and surface temperature relation and the correction of near surface air temperature difference (dT) in modified SEBAL. The fusion of ET derived from Landsat images and ET derived from NOAA-AVHRR images was also done. Application of modified SEBAL at a regional scale was performed using Landsat TM and NOAA-AVHRR imagery for the Sana’a basin, Yemen. The results indicated that modified SEBAL performed well for predicting daily and monthly ET for mountainous agricultural areas. Some results were obtained for volcanic areas, basalt areas, desert areas and also arid coastal areas, using prediction of surface parameters. Regional decision support system for ET was done in order to select the best or most suitable ET method, finally the proposed model for regional water balance shows good result for monthly data.


Page publiée le 13 décembre 2011, mise à jour le 10 avril 2020