الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
There are more than twenty-two separate vertical datum surfaces in the Arab world, all of them depend on the average readings of MSL measurements used to establish the vertical datums that were observed with an effect of the 18.6-year lunar tide gauges at a specific time. The mean sea level is used as a reference for height and still used until now although the average of this observed value does not exactly represent the geoid. In addition, the mean sea level at some sites differ in its value when it is compared with other sites because of the difference of equipotential surfaces. This is why the use of mean sea level as a reference causes a lot of problems that are associated with the application of vertical datum. The differences in Sea Surface Topography (SST) at tide gauge sites and differences in measuring techniques lead to delays in the implementation of regional projects in areas such as transportation, communication, and electricity reticulation grids and other projects that require heights. Therefore, the determination of a unified precise geoid represents a significant step in eliminating these differences as it forms the basis for the determination of regional geoid model.
This study focuses on presenting two proposals for unification the vertical datum in Arab region and the proposed implementation strategy, also it provides the best techniques to tie and unify the data (tide gauge stations, levelling, GNSS, and gravity points) in all Arab countries, commensurate with the modern technological development. After reviewing the available data from previous studies, and the researches in this field. . Some results can be concluded after implementing this proposed massive national project; Replacing the official levelling-based vertical datum all over the Arab region by unified precise geoid and GNSS
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compatible vertical datum, because it will be very easy to compute the orthometric height from unified precise geoid and precise ellipsoidal height. Easy to follow up the changes of mean sea level in different times to geodetic works and oceanographic surface and protection of coastline. All Arab countries together with desert, remote and extremist areas will contain unified vertical control system. Easy to determine the effect of SST in all Arab region. Consistently with space-based positioning (e.g., GNSS, altimetry) is going to be guaranteed. The maintenance of the unified vertical datum is going to be less expensive. The vertical datum is going to be fairly stable due the actual fact that the geoid surface changes at a rate of 1 mm annually compared to 1 cm annually for the physical benchmarks related to the regional geodynamics.
Finally, by documenting and depending on the Unified Arab Vertical Datum, the Arab nation will face the challenges of the globalization and will keep abreast with the continuous scientific progress. Because it will have an effective role in global agencies which interested in surveying, maps, and geodesy, like the International Association of Geodesy (IAG), International Center for Global Gravity Model (ICGEM), International Gravity Field Services (IGFS).