Evaluation of the Accuracy of GNSS-Based Cadastral Survey Methods in Kano Metropolitan Area

Cadastral surveying underpins secure land tenure, property registration, and dispute resolution in Nigeria. This study evaluates the positional accuracy of Global Navigation Satellite System receivers used for cadastral boundary demarcation in the Kano Metropolitan Area. Three GNSS methods, namely single-frequency static, Real-Time Kinematic, and differential correction, are compared against control points established by the Office of the Surveyor General of Kano State. A total of sixty boundary pillars distributed across peri-urban and core urban zones are resurveyed using each method, and root mean square error is computed for horizontal and vertical components. Results show that Real-Time Kinematic GNSS achieves the highest positional accuracy, with mean horizontal errors below five centimetres, satisfying the cadastral tolerance standards prescribed by the Survey Co-ordination Act. Single-frequency static surveys yield acceptable results in open terrain but are significantly degraded by multipath effects in dense built-up environments. The study identifies signal obstruction from tall buildings in the old city core as a major accuracy-limiting factor. Recommendations include the adoption of network RTK services, where feasible, and the deployment of permanent reference stations to improve coverage across the North West zone. These findings are directly relevant to ongoing efforts to digitise land records under the Kano State Geographic Information Systems Authority. Keywords: GNSS, cadastral surveying, positional accuracy, Kano, RTK.