The Components of Deflection of the Vertical Calculations for Heights in Computations and Adjustments of Physical Projects

The deflection of the vertical is an important parameter of the local gravity field which must not be neglected during survey measurements. In most survey (Geodetic) measurements, the components of deflection of the vertical are not considered as a result of non availability of detailed maps in such area or region. The components of deflection of the vertical using the GPS/levelling (Geometric) method were determined. Fifteen ancillary stations and one control station were used. The orthometric and the ellipsoidal heights of the stations were determined using digital Level and GPS respectively. The least squares adjustment principle was carried out on the observations with the components as parameters. The values obtained are: -0.550” ± 0.000001” and - 0.395” ± 0.0000006” for ξ (north-south) and (east-west) directions respectively. The components of deflection of the vertical of the study area were also computed using three geopotential models (EGM08, EGM96 and EGM84). They are: ξ = 0.179”, = -0.016; ξ = -0.150”, = 0.006 and ξ = -1.024”, = -1.355 respectively. It is recommended that carrying out physical constructions such as, buildings, roads, drainages, etc. that geoid model which serves as a reference surface for heights determination should be obtained by computing the components of deflection of the vertical