- Drone captured a 2.2 km2 georeferenced, temperature-calibrated thermal infrared radiation (TIR) orthophoto of the Waikite geothermal area.
- Calibrated thermal imagery and Monte Carlo analysis provides an estimate of a total heat loss of 43 ± 12 MW for thermal lakes and streams in the survey area (evaporation, conduction and radiation).
- Drone captured a 3km2 aerial photo and digital elevation model (DEM) of the Waikite geothermal area.
- This study demonstrates the capacity of drones to produce accurate thermal maps of large, inaccessible geothermal areas.
Drones are now routinely used for collecting aerial imagery and creating digital elevation models (DEM). Lightweight thermal sensors provide another payload option for generation of very high-resolution aerial thermal orthophotos. This technology allows for the rapid and safe survey of thermal areas, often present in inaccessible or dangerous terrain. Here we present a 2.2 km2 georeferenced, temperature-calibrated thermal orthophoto of the Waikite geothermal area, New Zealand. The image represents a mosaic of nearly 6000 thermal images captured by drone over a period of about 2 weeks. This is thought by the authors to be the first such image published of a significant geothermal area produced by a drone equipped with a thermal camera. Temperature calibration of the image allowed calculation of heat loss (43 ± 12 MW) from thermal lakes and streams in the survey area (loss from evaporation, conduction and radiation). An RGB (visible spectrum) orthomosaic photo and digital elevation model was also produced for this area, with ground resolution and horizontal position error comparable to commercially produced LiDAR and aerial imagery obtained from crewed aircraft. Our results show that thermal imagery collected by drones has the potential to become a key tool in geothermal science, including geological, geochemical and geophysical surveys, environmental baseline and monitoring studies, geotechnical studies and civil works.