Tauhara Field - Two Geothermal Systems?

Abstract

Although the four deep wells in the Tauhara Field indicate over 15 bar of drawdown due to of Wairakei Field, there have been no significant thermal or chemical changes to surface features on the south side of the Tauhara Field. The extent and concentration of chloride outflows in the Waipahihi seepage zone along the shores of Lake Taupo do not appear to have changed since the drawdown began in the late 1950s and The absence of significant changes to the south contrasts with the disappearance of chloride outflows along the banks of the Waikato River and increased steam-heating of groundwaters on the northern half of Tauhara Field. These differences suggest the southern side of Field has not been drawn down and therefore may be considered as a separate geothermal system. Subsidence trends are consistent with this interpretation.