PHYSICAL MODEL OF THE WAIRAKEI GEOTHERMAL FIELD, CIRCA 1960

Abstract

The Wairakei Geothermal Field physical model is unique. The model is built of wood; it was constructed in the late 1950s or early 1960s and is thus one New Zealand’s earliest physical models of geology; and it shows some features of the Wairakei Geothermal Field before the power production began in November 1958. These features include geological layers, well logs and temperature contours in area of the eastern and western borefields.
Temperature contours, mapped between 230°C and 255°C, demonstrated the utility of the physical model. Near-isothermal conditions in the eastern borefield were consistent with vertically-upwards flow of hot geothermal fluid to surface geothermal features whereas more variable ground temperatures in the western borefield were probably caused by mixing of hot geothermal fluid flowing from the west through ignimbrite units and cold groundwater moving through the shallower layers.