A new approach to prioritising groundwater dependent vegetation communities to inform groundwater management in New South Wales, Australia

Groundwater dependent ecosystems (GDEs) require access to groundwater to meet all or some of their water requirements to maintain community structure and function. The increasing demand of surface and groundwater resources has seen the NSW Government put in place management mechanisms to enable the sharing of water between irrigators, the environment, industry, towns and communities via water sharing plans. The groundwater sharing plans aim to provide adaptive management of GDEs by prioritising for protection those that are considered the most ecologically valuable within each plan area. The High Ecological Value Aquatic Ecosystems(HEVAE) framework has already been adopted to prioritise riverine ecosystems for management in surface water sharing plans. Here, we provide a method developed using the HEVAE framework to prioritise vegetation GDEs for management. The GDE HEVAE methods provide a derived ecological value dataset for identified groundwater dependent vegetation that is used to inform the planning and policy decisions in NSW. These decisions are required to manage and mitigate current and future risks caused by groundwater extraction. This is achieved via the identification of ecologically valuable assets to then use as the consequence component in a risk assessment for the groundwater sources, to provide vegetation GDE locations for setback distances for new groundwater production bores, and for the assessment of impacts due to current and potential future groundwater extraction. The GDE HEVAE method uses recorded and predicted spatial data to provide weighted scores for each attribute associated with the four HEVAE criteria (distinctiveness, diversity, vital habitat and naturalness). The combined scores categorise the ecological value of each groundwater dependent vegetation community (depicted as geographic information system (GIS) polygon features) from very high to very low. We apply the GDE HEVAE method to three catchments in order to demonstrate the method's applicability across the Murray-Darling Basin with varying elevation and climate characteristics. The ecological value outcomes derived from the methods have been used to inform planning and policy decisions by NSW Government processes to allow for protection in not only areas that are currently at risk but to also manage for potential future risks from groundwater extraction.