This paper focus on the establishment of Geodetic Network in Nigeria which serve as the framework and basis for every spatially referenced system in the country. It explains the historical development of Nigeria geodetic network, its mode of establishment, data acquisition method, computation and adjustment principles. The use recent positioning satellites (GNSS) and its several methods were discussed with the Least Squares Adjustment techniques. Literatures on best practices were reviewed to identify gaps that need to be covered so as to have an accurate and efficient geodetic network in the Nigeria. The research is basically on principles and methodology on the establishment of Geodetic Network in Nigeria and silent on hardware and software selection for its establishment.
Oyo state like most of the other states in the Nigeria has an old and conventional Geodetic Network. This network was established and computed using the conventional method of position determination and the science of navigation in the 1930- 1950's which is based on the 30th arc-meridian of the Clarke 1880 modified ellipsoid with its origin at L40 Minna datum. This does not satisfy the overgrowing mapping requirements of the state and as well as other Geo-related information requirements. The required data were acquired with GNSS receivers set up on each of the existing points in static mode. The reference network that was re- established consists of eight (8) primary points, covering an area of approximately ?12km?^2 with an average separation of about 7Km. The new network monuments are made of reinforced concrete, solidly cemented in the ground with metal caps (brass markers), and coordinated using the static carrier phase differential GPS measurement. Several observation sessions were conducted and processed to compute 3D coordinates for the network. Post processed data were rigorously adjusted using Least Squares and must meet the distance accuracy specifications for a first order network (1:100,000). Final coordinates are based on WGS84 frame/ ITRF 2008 datum and are within a mean accuracy of ±0. 05m. Finally, the plots of the re-established control points were presented and thus re-established a reliable first order geodetic reference network within Oyo state. Based on the findings the study recommends all geodetic networks in Nigeria should be re- established.
Given the security problem in Nigeria particularly in the North, the need for geospatial analysis of security in Bauchi metropolis in relation to police stations cannot be overemphasized. Apart from the prevalence of security problem in the area current analyses are inadequate, almost non-existent. To tackle this problem, Global Positioning System (GPS) was used to take the coordinates of the police stations in the study area, while the attribute data relating to the number of police personnel in each station were collected using interview and documented data. The data were analysed using simple ratio. Also ArcGIS (Version 10.0) software was used to show the map of the distribution. A nearest neighbourhood analysis has shown that the distribution of stations is random in the area. One and two kilometre buffer zones were generated and the result shows that the old city of Bauchi and the eastern part of the metropolis were fully served while the western and southern parts were underserved. The ratio of population in the area to a police is 898:1 which is far below the United Nation recommended figure of 450:1. The work recommends that there is need for population consideration in citing police stations in the area as well as increasing the work force as means for achieving a holistic security for the metropolis.
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