Ecosystems and water: environmental tolerances, responses and mitigation

Waterway

Aquatic ecosystems and water-dependent terrestrial systems (such as floodplain vegetation) can be highly dependent on the timing, quantity and quality of water in streams and groundwater.

Changes in water flows can also affect the connectivity of stream habitats. As such, it is important to understand the relationships between ecological health and water flow to avoid significant damage to these ecosystems.

Consideration is also given to how these issues contribute to the overall cumulative impacts of coal seam gas extraction and coal mining, according to different scales (local-regional) and timeframes (short-term to long-term).

Projects

Projects commissioned to date include:

Co-produced water - risks to aquatic ecosystems

This review captures the state of knowledge on issues associated with the quantity, quality, timing and potential risks to aquatic ecosystems from co-produced water, including:

  • impacts of changed surface water flow regimes and quality due to discharge of treated co-produced water
  • existing knowledge, including documentation on environmental impact assessments
  • examples of releasing co-produced water into natural flow regimes with a high seasonal variability
  • risk management frameworks and their applicability to coal seam gas and coal mining activities
  • industry practice in managing co-produced water.

Background Review:

Research to inform the assessment of ecohydrological responses to coal seam gas extraction and coal mining

This report presents the findings of a research program designed to improve understanding of ecological responses to groundwater drawdown associated with coal seam gas extraction and coal mining. The report consists of four interrelated components:

  • Ecohydrology of groundwater dependent terrestrial vegetation
  • Ecological values of baseflow and surface water-groundwater connectivity regimes in non -perennial streams
  • Hydrogeochemistry, biogeochemical processes and subsurface ecology
  • Biodiversity and risk assessment of Great Artesian Basin spring wetlands

The report highlights the importance of groundwater to ecosystem functioning and provides new tools for assessing the groundwater dependence of vegetation. The report also discusses the implications of the research findings for environmental impact assessment and monitoring in the context of coal seam gas extraction and coal mining developments.

Report:

Great Artesian Basin Springs Survey

This report is provided in two volumes and focuses on the history, ecology and hydrogeology of the Great Artesian Basin (GAB) Springs.

This report presents the research findings relating to the ecological and hydrogeological survey of recharge, discharge, and watercourse springs that could be impacted by coal seam gas (CSG) and coal development in the Surat and Bowen Basins. GAB springs occur in clusters known as supergroups, including the Springsure, Eulo, Bourke and Bogan River.

The 'community of native species dependent on natural discharge of groundwater from the Great Artesian Basin' is listed as endangered under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act), and thus this report presents results from surveys of all of the EPBC Act listed springs in these four supergroups. Surveying was undertaken in 503 springs in 94 spring complexes that had not previously been surveyed. The key findings include:

  • The EPBC Act listed spring community in the Springsure supergroup in the Surat Basin is most likely to be impacted by current coal seam gas development. The Lucky Last and Scott's Creek springs are of particular concern. These two spring clusters are habitat for the EPBC Act listed species Eriocaulon carsonii and have high conservation value. Other EPBC Act listed springs that may be impacted include Spring Rock Creek, Abyss and possibly Dawson River 8.
  • Groundwater data collection and modelling capabilities need to be improved to more accurately predict the impact of CSG extraction on aquifers that source springs in the Springsure supergroup.
  • CSG development and extraction are currently remote from active springs in the Eulo, Bourke and Bogan River supergroups, and are of less concern than the impacts of large free-flowing artesian pastoral bores that have not yet been rehabilitated.

Reports:

Modelling water-related ecological responses to coal seam gas extraction and coal mining

This report presents the findings of a project exploring an approach to ecological conceptual modelling aimed at improving the assessment of water-related ecological impacts of coal seam gas extraction and coal mining in Australia. The approach is presented as a series of consecutive steps and illustrated worked examples, and is aimed at assisting the preparation and review of environmental impact statements (EISs). Through the construction of ecological conceptual models and associated narrative tables that specify hypothesised responses and document supporting evidence, the assumptions about ecological impacts incorporated into EISs are made explicit, response pathways identified and interactive and cumulative effects illustrated. This provides a transparent and consistent framework for the design of monitoring programmes to test the implicit hypotheses.

This work highlights the need for the approaches to modelling and conceptualisation of hydrology and hydrogeology currently used in EISs to be extended to incorporate ecological components. This will facilitate the production of ecohydrological models capable of illustrating likely water‑related ecological responses to coal seam gas extraction and coal mining.

Application of the proposed approach is expected to:

  • enhance capability in the resources industries to identify and predict the water-related impacts of coal seam gas extraction and coal mining, through uptake of the approach to ecological conceptual modelling and integration of the ecological modelling approach with hydrological and hydrogeological modelling and conceptualisation
  • improve identification and understanding of the potential water-related ecological responses to coal seam gas extraction and coal mining in Australia, achieved through assisting the IESC in its evaluation of EIS documentation for coal seam gas and coal mining proposals and provision of advice to regulators
  • provide a framework for ecological conceptual modelling that could be drawn upon in the bioregional assessments.

Report:

Peat swamps - ecology monitoring

This report is one in a series of three reports focused on the Temperate Highland Peat Swamps on Sandstone (THPSS) ecological community and longwall coal mining.

The THPSS is listed as a threatened ecological community under the Environment Protection and Biodiversity Conservation Act 1999.

This report captures the findings of a research project that:

  • provided a hydrological and geological characterisation of the peat swamp communities
  • modelled the sensitivity of the swamps to changes in the surface and groundwater flows, and changes in water quality, caused by longwall mining
  • advised on the development of a monitoring and reporting approach to detect the potential impacts of longwall mining on the swamps.

This report was prepared using information that was publicly available as of early 2013.

Report:

Peat swamps - engineering subsidence

This report is one in a series of three reports focused on the Temperate Highland Peat Swamps on Sandstone (THPSS) ecological community and longwall coal mining.

This report captures the findings of a research project that:

  • reviewed information about subsidence-related ground movements, overburden caving mechanics and groundwater impacts, and assessed this information in relation to impacts on peat swamps
  • evaluated the opportunities for management of the impacts through prediction and engineering intervention, such as mine design alteration and provision for suitable buffers.

This report was prepared using information that was publicly available as of early 2013.

Report:

Peat swamps – remediation

This report is one in a series of three reports focused on the Temperate Highland Peat Swamps on Sandstone (THPSS) ecological community and longwall coal mining.

This report captures the findings of a research project that:

  • reviewed available information on THPSS and similar swamp communities and the way in which longwall mining can affect these communities
  • examined existing techniques used by industry for mitigating impacts on swamps
  • evaluated remediation techniques including information about restoration attempts at streams impacted by longwall mining.

This report was prepared using information that was publicly available as of early 2013.

Report: