Investigating groundwater dependent ecosystems
Ecological water requirements are one of the primary factors considered in assessing groundwater allocation options and managing the groundwater resources. However, evaluation of groundwater dependency by various environmental assets is always challenging. Even more challenging is an assessment of the risks to environment due to groundwater availability decline due to either anthropogenic groundwater use, extractive industry or changing climate.
Groundwater Dependent Ecosystems (GDEs) ultimately mark groundwater discharge zones. Discharge may result from the expression of groundwater at the land surface (e.g. baseflow or springs), directly from shallow watertable, or as groundwater uptake and transpiration by vegetation. Hence GDE investigation supports better characterisation of groundwater systems.
Detecting and monitoring groundwater dependent ecosystems
We are developing methods for detection, delineation and monitoring of GDEs habitats. This is achieved based on consideration of geological, hydrogeological and hydrological settings, available information of mapped vegetation and their typical ecohydrological characteristics as well as remotely sensed data analysis to define the spatial and temporal characteristics of GDEs. This allows us to classify GDEs on the likelihood of their groundwater dependency: from highly dependent (i.e. high likelihood of GDE occurrence), to partly dependent (i.e. medium likelihood of GDE occurrence), to non-groundwater dependent (i.e. lowest likelihood of GDE occurrence). The methods deploy various remotely sensed data: Landsat, MODIS, inSar among others. Particular advantages of remotely sensing techniques include the availability of historical satellite datasets and the ability to monitor large areas at low cost.
Furthermore, scientists from the Bioregional Assessment and Geological and Bioregional Assessment programs have developed new approaches and methods to assess cumulative impacts from extractive industry on groundwater dependent assets. Risks to GDEs from cumulative impacts of extractive industries, such as large coal mines and coal seam gas developments, were assessed by combining estimates of hydrological change, from groundwater and surface water models, with receptor impact models to quantify potential impacts on ecological assets. The hydrological models use uncertainty analysis to explore the effect of the range of plausible hydrological parameters, and in some cases conceptual uncertainty, on predictions of impact at a regional scale. Receptor impact models, meaningful relationships between hydrological response variables and receptor impact variables developed through expert elicitation, estimate potential impacts on and risks to ecological assets, such as GDEs.
Considering the environment in decision making
Our research in key locations across Australia including the Pilbara and in Northern Australia has resulted in a detailed understanding of the groundwater environmental services informing decision making process for groundwater resources allocation and improved management.