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Regional Geothermal Geochemistry Monitoring Programme (REGEMP) 11 Review: 2018 Interpretation of Geochemical Data

TR 2019/05
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Report: TR 2019/05

Author: Dr Nathaniel Wilson (Babbage)

About this report

This report is the fourth review of the Regional Geothermal Geochemistry Monitoring Programme (REGEMP), which Waikato Regional Council (WRC) recommenced in 2006 (i.e., REGEMP II). The purpose of REGEMP II is to collate geochemical data from surface geothermal features in the Waikato Region, and assess trends in the data that might assist in best management of the features.

The current review considered four distinct components:

  • Data integrity (the current state of the dataset)
  • Statistical analysis (similarities and differences between features)
  • Spatial analysis (how the chemistry changes by location)
  • Temporal analysis (changes over time)

The REGEMP review showed REGEMP II continues to produce valuable data about the region’s geothermal features. Based on the results of the review, the following has been recommended:

  • Add a site within the Tongariro area;
  • Consider a formal arrangement with GNS Science to collect and share data from features south of Taupo (to reduce sampling costs and travel times);
  • Continue to regularly collect regular physicochemical data (especially temperature) from features (at a more frequent rate than more comprehensive sampling occurs;
  • Collect isotope data every eight to ten years;
  • Investigate potential drivers for variation across parameters;
  • Investigate possible reasons for change in the temperature of features at Orakei Korako and Waiotapu;
  • Make data collation the focus of the next REGEMP II review.

A Shiny app was developed to provide interactive presentation of the results of the REGEMP survey. In addition, a review of laboratory service providers was undertaken to ensure that WRC was receiving the best service available.

Read or download the report

REGEMP II 2018 Interpretation of Geochemical Data [PDF, 3.6 MB]

Contents
  Executive Summary
1 Introduction
1.1 Background
1.2 Scope of Report
2 REGEMP Data
2.1 Data Sources
2.1.1 Waikato regional Council data
2.1.2 GNS Sciences data
2.2 Data Coverage
2.3 Data Selection
3 General Statistical Analysis
3.1 Approach
3.2 Hierarchical Cluster Analysis
3.2.1 Introduction
3.2.2 Results
3.2.3 Importance
3.3 Principal Component Analysis
3.3.1 Introduction
3.3.2 Results
3.3.3 Importance
3.4 Key points
4 Spatial Trends
4.1 Approach
4.2 Results
4.2.1 Physicochemistry: Temperature
4.2.2 Physicochemistry: pH
4.2.3 Cluster One: Boron
4.2.4 Cluster Two: Iron
4.2.5 Cluster Three: Magnesuim
4.2.6 Cluster Four: Chloride
4.2.7 Cluster Five: Arsenic
4.2.8 Isotopic data
4.3 Key Points
5 Temporal trends
5.1 Site Selection and Approach
5.2 Trends Over Time
5.3 Implications
6 Recommendations
7 Bibliography
Applicability and Limitations