Evaluation and Adaptation of the EGM2008 Geopotential Model along the Northern Nile Valley, Egypt: Case Study
Publication: Journal of Surveying Engineering
Volume 136, Issue 1
Abstract
The performance of the new EGM2008 global geopotential model (GGM), over the northern Nile valley and delta in Egypt, has been evaluated. Over 305 global positioning system (GPS)/levelling stations, the standard deviation of the undulation differences has been estimated to be 0.23 m. Thus, it can be concluded that the EGM2008 is superior to earlier GGMs over the northern area of Egypt by a factor of 1.6. Moreover, four mathematical models have been investigated in order to incorporate local data sets with the EGM2008, leading to the conclusion that the first-order polynomial is the optimum one. An improvement of about 26% has been obtained after applying that regression model, and the standard deviation has been decreased to 0.17 m. As a result, the EGM2008 produces a crucial influence on integrated GPS surveys where the orthometric heights can be obtained without any additional costs. Such a practice presents a suitable alternative, from an economical point of view, to substitute the expensive traditional levelling technique particularly for topographic mapping.
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Published In
Journal of Surveying Engineering
Volume 136 • Issue 1 • February 2010
Pages: 36 - 40
Copyright
© 2010 ASCE.
History
Received: Aug 19, 2008
Accepted: Dec 15, 2008
Published online: Mar 20, 2009
Published in print: Feb 2010
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