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Accueil du site → Doctorat → États-Unis → 2010 → Investigating the source of thermal anomalies in the northern United Arab Emirates (UAE) desert using geophysical methods

Missouri University of Science and Technology (2010)

Investigating the source of thermal anomalies in the northern United Arab Emirates (UAE) desert using geophysical methods

Ahmad, Khalid

Titre : Investigating the source of thermal anomalies in the northern United Arab Emirates (UAE) desert using geophysical methods

Auteur : Ahmad, Khalid

Université de soutenance : Missouri University of Science and Technology

Grade : Doctor of Philosophy (PhD) 2010

Résumé
"We conducted geophysical surveys to investigate the source of thermal anomalies and to delineate any potential water transport pathways from the recharge zones in the Oman Mountains to the location of the temporal thermal anomalies within the desert plain of the United Arab Emirates (UAE). In the visible region of the spectrum of both ASTER and MODIS satellite images, the desert plain of the UAE appears as a bare sandy surface. However, detailed examination of these images in the thermal bands reveal cooler thermal anomalies within the desert plain following major rainfall events. This anomaly has a cooler surface of approximately 20 °C lower than the surroundings with a lifespan of several days. It has been hypothesized that moist surfaces, following rainfall events in an arid hot desert could be an indirect indication of locations with groundwater accumulation. Two regional fault zones, Dibba (DFZ) (NE-SW) and Hatta (HFZ)(NWSE) were traced from ASTER satellite images and SRTM ( 90 m) elevation data, but it remained unclear whether they extend into the thermal anomaly area. Audiomagnetotelluric (AMT) and ground magnetic data were acquired to verify the possible extension of these fault zones into the thermal anomaly area. AMT data were acquired along profiles positioned perpendicular to the DFZ and HFZ trends and over a 3-D survey grid covering the anomaly area. The ground magnetic survey delineated the extension of both fault zones into the gravel plains area but not into the anomaly area probably due to the thicker sand cover. 2D AMT apparent resistivity sections show a low resistivity structure coincident with the thermal anomalies that parallel the DFZ trend. A conductive structure over the thermal anomaly area, coincident with the extension of the HFZ, was characterized from AMT 2-D inversions. The results suggest that the DFZ and HFZ extend from the recharge areas in the mountain into the desert plains. The results also suggest that these faults play a vital role in transmitting infiltrated rainwater from the Oman Mountains into the desert plain of the UAE where freshwater accumulates after rainfall events causing the thermal anomalies

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Page publiée le 31 décembre 2011, mise à jour le 9 octobre 2018