SURFACE HEAT LOSS FROM THE WAIMANGU GEOTHERMAL VALLEY

Abstract

The Waimangu Geothermal Valley is the youngest geothermal area in New Zealand. It was formed as a result of the 1886 Tarawera Rift eruption, and contains the world’s largest hot pool (Frying Pan Lake), numerous hot springs, fumaroles and areas of steam heated ground. Surface heat loss of the Waimangu Geothermal Valley is estimated in this study, using aerial thermal infrared imagery (TIR), collected on 28 January 2017, and a terrestrial calorimetry survey combined with chloride flux measurements undertaken in March 2017.
The terrestrial heat loss survey consisted of 19 calorimeter measurements in varying landcover. The measured heat flux of these sites are scaled-up using a new land-cover map, to determine a total surface heat loss of the valley. This surface heat loss estimate is combined with a calculated evaporative heat-flow from the surfaces of the two heated lakes, Frying Pan Lake and Inferno Crater.
The total heat loss for the Waimangu Geothermal Valley is estimated to be between 326 and 353 MW using the combined TIR and chloride flux techniques, and between 294.2 and 321.2 MW using the terrestrial calorimetry and chloride flux techniques. These total surface heat loss estimates are in close agreement with each other, and historic estimates.