Absolute gravity as geodetic reference control

Absolute gravity measurements with microgal accuracy represent a new tool for high accuracy vertical reference in properly selected distant sites. They offer therefore an ideal basis for control datum in Africa. As a by-product, eventual gravity changes with time can be followed (variations in water level depth, tectonic phenomena...) Essential is: proper selection of site, control of the local environmental conditions, establishment of a net of satellite stations to be tied with microgravimeters, and a firm program of regular repetition (each 5 or 10 years) of the absolute measurements.