Evaluating Positional Precision Of Adama City Gcp And Land Parcels: Case Of Adama City, Oromia, Ethiopia

Abstract

Accurate cadastral information is fundamental for effective land administration, urban planning, and the protection of land tenure. In rapidly growing urban centers like Adama City, Ethiopia, discrepancies between existing digitized cadastral data and actual ground positions have emerged as a major challenge for sustainable development. This study aims to assess the positional accuracy of cadastral land parcel boundaries by comparing existing digital records with high precision ground-truth data collected using Global Navigation Satellite System (GNSS) technology. A GIS-based least squares adjustment and Root Mean Square Error (RMSE) analysis were applied to evaluate spatial discrepancies between recorded parcel boundaries and actual ground positions. The findings revealed that zero-order GCPs achieved an average RMSE of 0.002 meters, and first-order GCPs recorded an RMSE of 0.003 meters, both satisfying the American Society for Photogrammetry and Remote Sensing (ASPRS) standard for horizontal accuracy (??? 0.0075 meters). However, second-order GCPs displayed RMSE values averaging 0.010 meters, and third-order GCPs reached 0.015 meters? both exceeding the ASPRS threshold. These results highlight that while the higher-order GCPs meet required standards, significant spatial inaccuracies exist in areas based on second- and third-order control points. The study identifies several potential sources of error, including outdated surveying techniques, improper georeferencing, and lack of periodic updates to the cadastral database. These inaccuracies compromise the integrity of cadastral records, leading to potential disputes over land ownership, inefficient planning, and challenges in land tenure enforcement. In conclusion, there is an urgent need for systematic updates to the cadastral system in Adama City. This includes re-surveying areas with low-order GCPs using modern GNSS technology, aligning cadastral datasets with current geospatial standards, and implementing a continuous validation and maintenance framework. Enhancing the positional accuracy of cadastral records will not only improve land administration but also support better governance, urban development, and tenure security in the city.