| Abstract |
The Karapiti Thermal Area is part of the Wairakei Geothermal Field and contains numerous steam-dominated features in an area of approximately 3 km2. Since 1952 there have been many changes to the surface features and thermal activity at Karapiti related to the development-induced pressure drawdown over most of the field. The hot chloride water originally underlying Karapiti has been replaced by a greatly expanded steam cap fed by a large low pressure steam zone in the Wairakei reservoir. There have been intermittent chemical surveys of the steam vents at Karapiti since 1951, with major chemical surveys undertaken in 1961 and 1990. In 1990, the concentrationsof were found to be about double the 1961values. Of particular interest is the change between 1936 and 1987 in gas chemistry of the main Karapiti feature, the Karapiti Blowhole which follows the change in heat flow from the Karapiti Thermal Area. Since the gas concentrations appear to be dropping to low, pre-development levels, most likely due to the decreasing pressures in the lower pressure steam zone. |