An enhanced geodetic network and geoid model for municipalities of Abu Dhabi Emirate

Nowadays, the combination of both an up-to-date geodetic network, with accurate positions and ellipsoidal heights, and a high accuracy gravimetric or hybrid gravimetric geoid model, is clearly the optimal combination to ensure accurate georeferencing of all survey works in both position and height, which is the prerequisite for efficient management of integrated land/water.

The availability of a dense CORS network allows obviously improving the integrity and accuracy of the related survey works while also providing a very convenient, cost-effective surveying and positioning solution. The availability of accurate complementary First order geodetic markers allow both strengthening the robustness of the survey works and providing redundant solutions for contingency in case of a CORS
failure. Finally, a hybrid gravimetric geoid model provides an accurate, convenient, height reference surface enabling all survey practitioners to obtain orthometric heights above MSL in the national vertical datum directly from GNSS observations.

From mid 2017 to mid 2019, Abu Dhabi Municipality and Fugro have executed a two-fold geodetic project intended to provide the Abu Dhabi Emirate with an accurate geodetic infrastructure. Abu Dhabi GPS Reference Stations network, consisting of 32 CORS, was recomputed in both ITRF2014 at Epoch 2019.0 and historical ITRF2000 at Epoch 2000.0, which allowed confirming significant station displacements for a number of CORS over the 12 last years. 53 new geodetic control points, consisting of pillars, were established to complement the AD GRS network. Gravity grids at 1 km and 2.5 km spacing, totalling more than 12,000 points were surveyed over the entire
Emirate, and 4 new absolute gravity stations were established across the Emirate, hence constraining the relative gravity network and avoiding error propagation. These grids were used to compute a high accuracy gravimetric geoid model, which was then fitted by least squares collocation onto the GPS-Levelling network for consistency purpose with the national Ras Ghumays vertical datum realization.

To be presented at the International Federation of Surveyors, FIG Conference, 10-14 May 2020