Gravimetric Geiod Determination of Okenya Town, Idah, Kogi State, Nigeria

International audience Adequate geospatial infrastructure, which is fundamental to growth and development of any nation, is generally incomplete without the realization of the height system of the nation. In order to achieve a sound geospatial infrastructure, the geoid must be determined and with a geoid model in place, 3D position of points can easily be measured using the Global Navigation Satellite System (GNSS). This paper examines the practical realization of the Gravimetric Geoid Model of Okenya Town, Idah, Nigeria using a Modified Simple Pendulum. Gravity data were obtained randomly within the town and the study area was gridded into thirty-six compartments at 30" interval. Gravity data reductions were carried out via the Free-Air and Bouguer Plate corrections. A gravimetric geoid undulation model was thus computed from the available 295 gridded gravity anomalies using the Modified Stokes Integral. Statistical analysis showed that the mean geoid undulation was 20.895m. The evaluated geoid undulation profile was validated by comparing the standard deviation of geoid undulation as computed from Stokes Integral and that of a Geometric Geoid model of the town and they were found to be 0.3157965 and 0.313212401 respectively. The average covariance function of the free air gravity anomalies was evaluated to a value of 11811.059milligals and had an estimated root mean square (r.m.s) free air gravity anomaly value of 108.679milligals. The modified simple pendulum apparatus was recommended for gravity data generation, since it is cheaper than any other method, it is simpler and sources of error are minimal. It also confer on researchers absolute responsibility of the data so generated as compared to the gravity data already generated by different agencies at different times, which we cannot testify to their general correctness.