Oral Presentation NCGRT/IAH Australasian Groundwater Conference 2019

Development of a groundwater health index (291)

Louise Weaver 1 , Judith Webber 1 , Phil Abraham 1 , Erin McGill 1 , Bronwyn Humphries 1 , Pierre-Yvres Dupont 1 , Annette Bolton 1
  1. ESR Ltd, Ilam, Christchurch, CANTERBURY, New Zealand

Within groundwater there are a whole range of organisms from micro to macroscopic that live in a complex ecosystem.  These ecosystems protect our groundwater by removing contaminants and maintain porosity and flow.  The processes that occur in these systems is still largely a black box and there are many potentially vital ecosystem services that occur that we still do not fully understand. 


Our project is aimed at ultimately establishing a groundwater health index that can be used, similar to the macroinvertebrate community index (MCI) in surface water systems.  Our research is not only focused on the macroinvertebrates present but the microbial diversity as well. 

Design and Methodology

Groundwater samples, in-situ biofilm bag samples have been collected at sites in New Zealand over multiple seasons.  The water chemistry is analysed with the 16s rRNA sequence data (targeting bacteria, archaea, fungi, and eukaryotes) to provide the basis of a method to identify the status of a groundwater source.

Original data and results

We have shown there is a complex diversity present in both the groundwater itself and the attached microbial biofilm.  We have shown this variation between the attached and groundwater occurs across all sites studied and significant differences in the Shannon richness indicator seen in Canterbury (Wilcoxon rank, p = 4.6 x 10-7).  We also find there are differences occurring in groundwater and attached microbial populations depending on the lithology and water chemistry present. 


Our research is identifying key species (micro and/or macro) present that can potentially act as a tool for predicting the health of a groundwater.  An additional benefit of understanding the biological processes that are occurring in our groundwater is that beneficial organisms capable of remediation could be discovered.