THE DEVELOPMENT AND VALIDATION OF AN EGM2008 GEOID MODEL FOR SENEGAL.

In Senegal, the use of GPS Global Navigation Satellite Systems (GNSS) technology to give a planimetric position on the WGS84 ellipsoid has increased considerably in recent decades. However, the problem of altitude posed by this technology presents the engineers a complex obstacle, since it is necessary to determine with precision the orthometric position of an object on the surface of the Earth, in particular within the framework of the projects of equipment engineering of the territory or geophysical work. Indeed, a precise determination of the orthometric height obtained most often by leveling is fundamental for a good execution of the projects of civil engineering, public works and territorial development. The use of several altitude reference surfaces (IGN, NGAO, NGS) further complicates the engineers\' task thus increasing the risk of costly errors and biases in the conduct of public works and civil engineering. The solution to this problem of precision is the development of a local geoid model for Senegal adapted to the EGM2008 model, which remains a major development in the modeling of Earth\'s gravity and geoid.