Thermal UAS survey of reactivated hot spring activity in Waiwera, New Zealand

The utilization of geothermal reservoirs as alternative energy source is becoming increasingly important worldwide. Through close-range aerial photogrammetry realized by unmanned aircraft systems (UAS), this study investigates the surface expression of a leaking warm water reservoir in Waiwera, New Zealand, that has been known for many centuries but remained little explored. Due to overproduction during the 1960s and 1970s the reservoir has suffered significant pressure reduction, which resulted in the loss of artesian conditions and led to the desiccation of the hot springs in close succession. However, shortly after the recent shutdown of the primary user (Waiwera Thermal Resort & Spa) renewed artesian activity was reported by locals but no hot spring activity has been observed so far. Therefore, this study was carried out in October 2019 to assess the actual conditions of thermal activity in the area of the former hot springs. UAS with coupled thermal infrared cameras were used for thermal mapping and the obtained data show renewed activity of the hot springs on the beachfront of Waiwera. Faults and fractures were identified as important fluid pathways, as well as individual fluid conducting lithologies.