Definition and Listing of Significant Geothermal Feature Types in the Waikato Region

Abstract

The Waikato Regional Council is developing policies for assessing a suitable balance between use and environmental protection of geothermal resources within its regional boundaries. One of these developments involves attempting to determine a rational approach for establishing criteria for protection by defining Significant Geothermal Features and the present paper outlines progress to date with this endeavour. We define geothermal feature types, and then attempt to assess the degree to which they require special efforts at protection based on considerations of rarity and vulnerability. We identify clearly the types of feature according to the geothermal processes that create and sustain them. We also define the "area" of each type of feature in order to provide certainty as to what we regard as being its surface boundary.
We suggest a particular numerical representation scheme for each of the factors "rarity", "vulnerability to natural changes" and "vulnerability to artificial changes" as applied to each geothermal feature type, and then in due course we shall argue for a way in which these numbers should be combined in order to assess an "endangerment index" for each type. This is then available for possible use in defining the degree of protection that such a feature type deserves in order to ensure that New Zealand retains a full range of the different types, and sufficient examples of each type.
A count of the number of occurrences of a particular type of geothermal feature is, in some cases, too naÔve a way to assess its rarity. This is because some features are of easily recognisable and limited physical size while others are of indefinite size. We call the first intensive entities and the latter extensive entities. We suggest a method for putting these two entities on an equivalent footing.
When considering vulnerability, we first concentrate on effects caused by natural changes including meteorological influences and then address responses to changes induced by human agency.