Assessing groundwater storage changes in the Nubian aquifer using GRACE data

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• 作者：Ahmed M. Yosri ; Mohamed A. Abd-Elmegeed ; Ahmed E. Hassan
• 刊名：Arabian Journal of Geosciences
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：9
• 期：10
• 全文大小：6,347 KB
• 刊物类别：Earth and Environmental Science
• 出版者：Springer Berlin Heidelberg
• ISSN：1866-7538
• 卷排序：9

文摘

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 with specific degree and order. The GRACE data is de-correlated using a sixth 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 parity. The GRACE estimates of GWSC are smoothed using Gaussian filter with half width of 1000 km. This half width is chosen in order to maximize the correlation between the GRACE estimates of GWSC and previous modeling results of the NSAS. The loss in groundwater storage occurring in each of the four countries sharing the NSAS is calculated to assess the sustainability of using the NSAS as a water resource in each country. The overarching finding in this study is that NSAS is losing its groundwater storage at a very high rate. Also, it is found that Egypt is the fastest in losing its groundwater storage from the NSAS. This loss of groundwater storage in Egypt may not necessarily be resulting from in-country extractions because of the trans-boundary nature of this aquifer. The GRACE-based estimates are found to be close to available data and previous modeling results of the NSAS.KeywordsGroundwater storageGraceNubian aquiferArid regions