Biodiversity Month

Let’s talk GDEs

September is Biodiversity Month, so what better time to talk about one of our favourite acronyms, GDEs – Groundwater Dependent Ecosystems. 

Which ecosystems rely on Groundwater?

Groundwater is water that exists within pore spaces and fractures in sediment and rock below the Earth’s surface. This water has been collecting from rainfall and streamflow over time, with over a thousand times more water stored below ground, than is in the world’s rivers and lakes. 

This huge reserve of groundwater supports ecosystems that exist below surface in aquifers and caves, referred to as subterranean fauna. As well as terrestrial GDEs, such as riparian vegetation and deep-rooted trees reliant on shallow groundwater, aquatic GDEs are reliant on the surface expression of groundwater; including rivers, springs, swamps and caves.

The occurrence of GDEs is influenced by the local geology, geomorphology, groundwater conditions and ecosystem types. To understand if there might be GDEs in your area, you can access the online interactive tool developed by The Bureau of Meteorology. A formal assessment of the relevant ecosystem in your area is important, to confirm definitively if there is a GDE present, and its nature.

What factors affect the sustainability of GDEs? 

The resilience and survival of GDEs can be impacted by changes in climate, land use and groundwater demand. Threats to GDEs include changes to groundwater quality and or changes to groundwater levels, either as a decline due to reduced recharge, groundwater interception and over abstraction, or a rise and waterlogging due to land clearing or changes to drainage and flow.

Are GDEs protected by Government regulation? 

Yes. GDEs are recognised at both a State and Commonwealth levels of government for their importance to the community and environment we live in. Under the environmental impact statement process for major developments, assessment of impacts to GDEs is required. State governments have released guidelines for the identification, assessment and management of GDEs. This includes the Queensland government GDE terms of reference and the NSW government Aquifer Interference Policy impact considerations for GDEs. In 2019 the Commonwealth also released the Information Guidelines Explanatory Note Assessing groundwater-dependent ecosystems.

How has Umwelt contributed to how we understand GDEs? 

Understanding of GDEs is continually growing, with studies conducted by government agencies, universities and private industry across Australia. Umwelt Australia is proud to be a part of this growing research into GDEs, with our combined teams of ecologists, hydrogeologists and surface water engineers experienced at conducting field surveys, undertaking tailored ecohydrological assessments and developing groundwater dependent ecosystem management plans (GDEMPs).