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sur le développement des zones arides et semi-arides

Titre : Assessing Groundwater Storage Changes in the Nubian Sandstone Aquifer using Gravity Recovery and Climate Experiment (GRACE) Data

قييم التغيرات فى المخزون الجوفي للخزان النوبى باستخدام بيانات تجربة إستعادة الجاذبية والمناخ

Auteur : Ahmed M.Yosri Ahmed Bakry

Université de soutenance : Cairo University

Grade : Master of Science (MS) 2015

Résumé
Gravity Recovery and Climate Experiment (GRACE) level two (L2) data is used in estimating the groundwater storage changes (GWSC) in the Nubian Sandstone Aquifer System (NSAS). This set of data consists of spherical harmonics coefficients (C and S) with specific degree (L) and order (m). The GRACE data is decorrelated using a 6th degree polynomial in order to reduce the effect of the noise error resulting from the correlation between the spherical harmonics coefficients with the same degree (L) parity. The GRACE estimates of GWSC are smoothed using Gaussian filter of half width equals 1000 km. This half width is chosen in order to maximize the correlation between the GRACE estimates of GWSC and the modeling results. The loss in groundwater storage occurs in each country of the NSAS sharing countries is calculated in order to assess the potential of using the NSAS as a groundwater source in each country. The overarching finding in this study is that the Nubian sandstone aquifer is losing its groundwater storage at a very high rate and that Egypt is fastest in losing its groundwater storage from the NSAS. Due to the trans-boundary nature of the NSAS, the loss of storage in Egypt may not necessarily be resulting from in-country extractions. These GRACE based estimates are close to available data and modeling results of the NSAS.

Mots clés : GRACE, Groundwater, NSAS

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