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Accueil du site → Doctorat → Allemagne → 1999 → Modelling and measurement of soil moisture content based on a remote sensing method for applications in semi-arid tropics

Rheinischen Friedrich-Wilhelms-Universitat Bonn (1999)

Modelling and measurement of soil moisture content based on a remote sensing method for applications in semi-arid tropics

Baanda A Salim

Titre : Modelling and measurement of soil moisture content based on a remote sensing method for applications in semi-arid tropics

Auteur : Baanda A Salim

Université de soutenance : Rheinischen Friedrich-Wilhelms-Universitat Bonn

Grade : Doctor 1999

Résumé
Soil moisture plays a very crucial role in land surface processes. It should therefore be monitored with the same accuracy and frequency as other important environmental variables. Two approaches are used for estimation of soil moisture content, namely, modelling and measurement, either in-situ or remote. Integration of modelling and measurements may provide the best solution towards estimation of soil moisture content. The utility of ground-based thermal infrared remote sensing method for the estimation of near-surface soil water content was tested under tropical semi-arid agricultural conditions in Morogoro, Tanzania, East Africa. Field experiments were conducted between January and August, 1997 at a bare soil site. Regression relationships between the daily maximum surface soil temperature minus air temperature (TDMax) and weighted-average soil water contents to different depths in the soil profile were developed based on the measured data. Better correlations were obtained for the top 0-5 and 0-15 cm layers of the soil, with coefficients ofdetermination of O.81 and 0.78, respectively A physically based model of coupled flow of heat and water in the soil (SUAHEAT) was developed. The SUAHEAT model was tested by comparing its simulated soil water contents and soil temperatures with those measured at the bare soil site. Both qualitative as well as quantitative methods were used to evaluate the model performance, for the calibration and validation phases. For the calibration phase, the average values of the mean absolute difference (MAD) of soil water content were 0.06, 0.05, 0.05, and 0.03 m3/m3 for the 5, 15, 30, and 45 cm depths, respectively. The performance of the model in the simulation of surface, near-surface, and profile soil temperatures was also both qualitatively and quantitatively evaluated. ]n the calibration phase, the M AD values were 2.8, 1.1, 0.5, and 0.3 °C for the 5, 15, 30, and 45 cm depths, respectively. Generally, the errors obtained with the use of the SUAHEAT model are comparable to values obtained by other researchers elsewhere using simillar models.

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Page publiée le 13 novembre 2015, mise à jour le 10 mai 2019