Surface modelling by geoid determination for flood control of Ewekoro limestone deposit (Nigeria)

Purpose. To determine the geoid heights from various control points of the quarry located in the northern and southern zones of the limestone deposit of the Lafarge WAPCO Cement Ewekoro in Ogun State, Nigeria. Methodology. The GPS and levelling data were used to determine the geoid heights from various control points of the quarry located in the northern and southern zones of the limestone deposit. The geoid heights obtained from GPS-Levelling data were used for three surface models which are polynomial regression model, inverse distance model and nearest neighbour model. These models were used to crossvalidate the geoid heights for the control points. Findings. The result shows that the deviations of the geoid heights for the GPS/Levelling and models are between 0.03 and 0.01m respectively. The models were used to generate contour maps that reveal the better location where the flood can be channelled. Originality. The results can be compared to the data obtainable during operations carried out in the quarry. Practical value. The flood in the quarry face will be better controlled by creating a sump at the lowest point on the elevation maps and controlled drilling to give better aeration.