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Estimation régionale de l'évapotranspiration sur la plaine de Kairouan (Tunisie) à partir de données satellites multi-capteurs

Abstract : The main objective of this thesis is to understand the functioning of a semi-arid ecosystem by developing methodologies from combined optical and microwave satellite measurements in order to assess evapotranspiration and its seasonal dynamics in a semi-arid region (Kairouan plain). The retrieving of the latter requires a good description of the vegetation dynamics and monitoring the water content in the soil. For this purpose, an analysis of vegetation dynamics is made on the basis of the SPOT VEGETATION time series from 1998 to 2010. To understand the vegetation behavior along frequent periods of drought, fractal analysis is an appropriate tool to study the vegetation persistence. A new statistical index referred to VAI "Anomaly Vegetation Index" describing the state of vegetation water stress is proposed. This quantitative index can be used to describe at a monthly scale the state of vegetation. Several validation approaches are implemented to test the performance of this index that confirms its reliability. In terms of monitoring the soil water content, moisture products derived from ERS and ASCAT / Metop scatterometer are availables. These products are validated in our study using two different approaches. A statistical drought monitoring index is proposed from a long time series of moisture products that covers twenty years (from 1991 to 2010). The index proposed referred to MAI "Moisture Anomaly Index" is based on anomaly analysis of temporal variability of soil water content, estimated from ERS and ASCAT / Metop scatterometers. A comparative analysis with other drought indices, particularly SPI "Standardized Precipitation Index" is made and shows the performance of our index. This information derived from the two time series optical and microwave are then integrated into a simple and operational model FAO-56 (dual crop coefficient approach) for mapping at a daily scale the evapotranspiration at 1km resolution. A validation of this approach is generated by comparing the results with the outputs of a SVAT model: ISBA-A-gs.
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Submitted on : Tuesday, January 7, 2014 - 4:42:46 PM
Last modification on : Monday, July 4, 2022 - 9:29:00 AM
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  • HAL Id : tel-00925198, version 1

Citation

Rim Amri. Estimation régionale de l'évapotranspiration sur la plaine de Kairouan (Tunisie) à partir de données satellites multi-capteurs. Instrumentations et Détecteurs [physics.ins-det]. Université Paul Sabatier - Toulouse III, 2013. Français. ⟨tel-00925198⟩

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