| Title | GROUNDWATER CIRCULATION SYSTEMS OF HIGH-TEMPERATURE GEOTHERMAL FIELDS IN THE UPPER WAIKATO CATCHMENT, TAUPO VOLCANIC ZONE, NEW ZEALAND |
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| Authors | P.A. White and R.R. Reeves |
| Year | 2017 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Water budgets, geothermal system recharge, groundwater recharge, upper Waikato River, Taupo Volcanic Zone |
| Abstract | Groundwater circulation systems provide recharge to high-temperature geothermal fields in the Upper Waikato catchment, Taupo Volcanic Zone (TVZ), and are integral to surface hydrology as they provide baseflow to the Waikato River and its tributaries from springs (hot and cold) and seeps. This paper calculated some characteristics (i.e., catchment location and water budget) of groundwater circulation systems associated with 14 geothermal fields in the Upper Waikato catchment. These characteristics were identified with: a three-dimensional geological model that included 17 hydrogeological units (e.g., basement greywacke, major ignimbrite groups, volcanic cones and domes, lake sediments and faults); a piezometric map that represented static groundwater elevation; and groundwater budgets that identified major flows, e.g., rainfall recharge and groundwater outflows that were associated with the catchments of geothermal fields. The groundwater catchments showed where the geothermal fields were linked geographically, and probably hydraulically. Two types of links were identified: inflows to some geothermal fields that may share a common ‘deep’ groundwater source, e.g., the major cluster of fields located on the flanks of the Paeroa Range (i.e., Reporoa, Waiotapu, Waikiti, Te Kopia and Orakei Korako); and where groundwater catchments may be linked by outflows (e.g., the Tauhara and Wairakei fields). Together, the characteristics of the groundwater catchments indicated some factors controlling geothermal field location. Therefore, this paper has identified groundwater hydrology as a valuable tool for the investigation of geothermal fields at local, and regional, scales. |