Unmanned Aerial Vehicle for Topographical Mapping of Inaccessible Land Areas in Ghana: A Cost-Effective Approach

The use of Unmanned Aerial Vehicles (UAVs) for remote data acquisition has rapidly evolved in recent years. The integration of UAV with Global Positioning System (GPS) and Geographic Information System (GIS) techniques have reduced time and cost in acquiring data for inaccessible land areas. Topographical mapping of water bodies, marshy areas or land areas without land cover using traditional methods of surveying in Ghana is time consuming and challenging. This study considered topographical mapping of muddy Tailings Storage Facility (TSF) sites at a rain forest mining area at Osino in the Eastern Region of Ghana. DJI Phantom 4 Pro consumer UAV was flown at an altitude of 75m in a 3D flight mode. Real Time Kinematic (RTK) GPS was used to coordinate a reflective-marked Ground Control Point (GCP). Georeferencing the orthophoto was done using the GCP. Digital Terrain Model (DTM) was generated from the processed orthophotos after which contours at 5 m interval were generated. Cross sections across the TSF were drawn for further geotechnical and stability analysis for the tailings dam. The accuracy of the topographic map is below 5 cm and confirms the suitability of using consumer grade UAVs for topographical mapping of inaccessible areas in a cost-effective manner. Thus, the integration of RTK technology with the UAV and GIS is a feasible and appropriately accurate solution for mapping inaccessible areas.