The Rotorua Geothermal Field: An experiment in environmental management

• Published in: Geothermics 2016-01, Vol.59 (Part B), p.294-310
• Main Authors: Scott, B.J., Mroczek, E.K., Burnell, J.G., Zarrouk, S.J., Seward, A., Robson, B., Graham, D.J.
• Format: Article
• Language: English
• Subjects: Chemistry; Economics; Environment management; Geothermal; Geothermal field management; Geothermal resources; Heat flow; Hydrothermal eruptions; Mathematical models; New Zealand; Preserves; Recovery; Regional planning; Rotorua; Rotorua Geothermal Field; Surface geothermal features; Trends
• ISSN: 0375-6505; 1879-3576
• DOI: 10.1016/j.geothermics.2015.09.004

•Rotorua Geothermal Field is showing some signs of recovery after the bore closure programme, confirming effectiveness of the Rotorua Geothermal Regional Plan.•Chemistry of bore waters and surface features help define the hydrological model and confirm recovering surface features contain same geothermal fluids as before their failure.•Reservoir modeling can match data from monitor bores.•Repeat heat flow surveys show declining trends continue in surface features at Whakarewarewa.•Recovery of surface features remains variable. The Rotorua Geothermal Field (RGF) is a unique example of a geothermal system that has been managed intensively to both obtain energy in a sustainable manner and to preserve the surface features and their intrinsic value. The field underwent an extensive bore closure programme in the 1980s. Exploitation today is characterised by a reduced number of shallow bores (140 consented bores and an additional 42 with down hole heat exchanges) with limits set on use by a management plan designed and monitored by the Bay of Plenty Regional Council. The RGF has a wide range of uses, values and differing significance to the Rotorua community, including cultural values, economic benefits, energy source and a tourism driver. A collection of research and monitoring activities are presented in this paper. We summarise the current management regime, surface feature trends and results of chemical research, repeated heat flow surveys at Whakarewarewa and representative temperature-contour maps of the geothermal resource. These data and results show that the composition of the primary deep fluids have changed little over time, while marked physical changes have occurred at surface features; a mix of positive recovery signs, along with many complex exceptions to those trends are seen. The use of modern numerical modelling methodology, using bore temperature records, geology and chemical data allow for improved modelling of the system.