Application of the groundwater health index (GHI) as a water monitoring tool.

Full description

Under various legislations, NSW Department of Planning, Industry and Environment (DPIE) is required to ensure the sustainable and integrated management of groundwater, as well as providing for the protection of water sources, their associated ecosystems, ecological processes and biological diversity.

The ongoing provision of clean groundwater depends on healthy groundwater ecosystems containing microbes and invertebrates (stygofauna). These biota improve water quality and aid water flow. Without the sustainable management of groundwater, it is likely that the health of these ecosystems will decline, with consequence of declining groundwater quality and availability, which may result in increased costs for groundwater extraction and water treatment to make water fit for purpose.

In 2011, a groundwater ecosystem monitoring program began in northern NSW. From this, the Groundwater Health Index (Korbel & Hose 2011; Korbel & Hose 2017) was developed. This method allows groundwater health to be assessed and monitored using a combination of biological and water chemistry variables. Since 2017, this method has been utilised in Europe as a potential framework for adoption in the Groundwater Framework Directive, with recent publications demonstrating its use in assessing groundwater health (e.g. Di Lorenzo et al 2020).

This project aimed to fill critical knowledge gaps and enable the performance monitoring of WSP and WRP strategies for groundwater dependent ecosystem and to meet water quality management plan targets for GDEs.

The project sampled groundwaters in shallow alluvial aquifers of the Lachlan, Murrumbidgee and Murray sub-catchments of the southern Murray-Darling Basin (MDB) within NSW. It has successfully provided:

· Documentation of the extent and condition of subterranean GDEs in the region

· A first ever assessment of the groundwater microbial and invertebrate biodiversity in the region

· Baseline data on groundwater chemistry and groundwater water levels

· Improved groundwater ecosystem sampling methodologies

· Application of the GHI to assess overall groundwater health within these 3 sub-catchments

The outcomes from this work highlight the biodiversity contained within aquifers of the MDB, and their roles in the maintenance of water quality. The method employed provides an improved groundwater management program, shifting from the current approach of monitoring water levels and occasional sampling of physico-chemical parameters such as pH, electrical conductivity, to an approach that considers groundwater biodiversity and the maintenance of ecosystem function and services. It will allow for future assessment of potential groundwater health decline and promote ecological sustainability and natural resource stewardship, while concurrently improving the capacity for the future management of this resource.