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Free keywords:
Waiwera; Geothermal; UAV; Hot spring; Thermal infrared; TIR; Remote sensing; Resource management
Abstract:
Remote sensing can be used to identify subtle natural geothermal surface features and assist with follow-up mapping and sampling. This study presents the use of repeated aerial thermal infrared (TIR) surveys at Waiwera to monitor recovery of artesian flow in low-temperature systems and demonstrating how repeat TIR surveys can be used in ongoing management of surface features. At Waiwera, overuse of the geothermal system caused coastal artesian springs to cease flowing in the 1960s. The main user of geothermal water in the area, Waiwera Thermal Resort, closed in February 2018, and there is now evidence of the geothermal system rapidly recovering pressure, resulting in artesian conditions, and causing bores to overflow. TIR surveying has confirmed springs have restarted discharging geothermal water and compared results with a 2019 UAV TIR survey. Flowing warm water fractures on the intertidal shore platform have water temperatures of between 15.0°C and 34.4°C. The springs have increased in temperature between October 2019 and May 2022. Thermal anomalies are unconnected to overland flow from storm water drains. Controlling overflowing bores may allow the coastal artesian springs to return to their historic recreational use.
