Aerial Thermal Infrared Survey of the Buranga Geothermal Prospect, Uganda

Abstract

A drone-based aerial thermal infrared (TIR) and high resolution color imaging survey at the Buranga geothermal prospect in Uganda was completed in 2018 to facilitate safe access for exploration programs, constrain structure and shallow aquifer mapping, support heat flow estimates and provide environmental baseline imaging. About 2000 thermal images were captured by a drone over a period of 3 days and compiled to produce a 0.8 km2 georeferenced, temperature-calibrated thermal orthophoto map with a pixel width of about 13 cm and positional error under 3.5 m. The complementary visible light color orthophoto map had a pixel width of 2.5 cm. High-resolution imaging was required for the survey because the wetland vegetation of Buranga would otherwise obscure the numerous small hot spring vents that are characteristic of the prospect. The TIR imaging was correlated with over 75 shallow temperature measurements made with ground probes in order to validate the completeness of the ground mapping and support the interpretation of the TIR imaging with respect to temperatures 10 to 30 cm below the ground surface or in mud below shallow water. The TIR confirmed that the ground probe surveys had been thorough in mapping the area of the 75 vents but had missed a few thermal features separated from the main vent clusters and obscured by vegetation or shallow water. This extended the area affected by the shallow hot aquifers at Buranga.