3.7.4 Gaps, limitations and opportunities

This impact and risk analysis allows governments, industry and the community to focus on areas that are potentially impacted when making regulatory, water management and planning decisions. Due to the conservative nature of the modelling, the greatest confidence in results is for those areas that are very unlikely to be impacted (that is, outside the zone of potential hydrological change). Where potential impacts have been identified, further work may be required to obtain better predictions of the potential magnitude of impacts to ecosystems and individual assets.

Key knowledge gaps have been identified in each of the Gloucester reports. This section provides a summary of the key knowledge gaps where understanding the potential impacts of coal resource developments can be improved through further work. Overall

Additional coal resource development is likely to be in the northern half of the subregion, with an expansion of the Stratford mine and a new mine at Rocky Hill, along with Stage 1 of the Gloucester Gas Project. As a result, groundwater drawdown and changes in streamflow are also greater in this part of the subregion potentially impacting an area north-east of Stratford and including Avondale Creek, Dog Trap Creek, Waukivory Creek, Oaky Creek and the Avon River. Any additional monitoring of groundwater levels and/or surface water should therefore focus on these areas. Assessing ecological impacts

Additional vegetation mapping and ongoing research to identify groundwater-dependent ecosystems in the subregion would improve assessment of impacts on water-dependent assets. Additionally, tracking the biophysical processes, such as rate of actual evapotranspiration and vegetation growth rates, of the groundwater-dependent ecosystems and interpreting these in an ecohydrological framework will improve understanding of the interactions between changes in groundwater availability and the health of terrestrial vegetation that relies on groundwater. This can be performed by field measurement and/or use of time series remote sensing.

As actual water requirements of different plant communities are only approximately known, future assessments would be assisted by more work to identify suitable bio-indicators of ecosystem condition, or alternative methods of assessing the condition of water-dependent ecosystems. Again, this is likely best performed using field measurement and/or time series remote sensing. Groundwater data and mapping

Groundwater data available from state databases include primarily monitoring data for shallow groundwater systems and aquifers used for irrigation, stock and domestic purposes. These data are usually in the form of water level measurements and major ion analyses which support knowledge of groundwater recharge processes and interactions between rivers and groundwater. However, this information provides limited understanding of deeper groundwater systems which are targeted by CSG development. This has been factored into the assessment’s uncertainty analysis and modelling. Future assessments would be assisted by improved information on deeper groundwater systems.

Also, future investigations of the mapping of depth to groundwater, and its spatial and temporal variation, would improve confidence in assessment predictions. Interactions between changes in groundwater availability and the health and persistence of terrestrial groundwater-dependent vegetation remain uncertain due, in part, to sparse mapping of groundwater depths outside of alluvial layers.

Drawdown predictions are very sensitive to hydraulic properties of the deeper sedimentary basin, especially predictions of the surface weathered and fractured rock layer. Improved knowledge of the hydraulic properties of the surface weathered and fractured rock layer and storage is needed to better understand groundwater changes at different depths. Geology

Groundwater modelling conducted in this assessment demonstrates that faults are likely to have minimal impact on changes in groundwater due to additional coal resource development. However, there remains a knowledge gap in the geological understanding of the Gloucester geological basin regarding the number of faults, their orientations and other physical characteristics.

The modelling did highlight that improved characterisation of hydraulic properties of the surface weathered and fractured rock layer and more detailed information of local geology around developments have the most potential to reduce predictive uncertainty. Water quality

Changes in water quality parameters that could occur with a shift in the relative contributions of surface runoff and groundwater to streamflow or due to enhanced connectivity between aquifers of differing water quality, for example, are not represented in the models. Modelling the changes in water quality was not part of the scope of the bioregional assessments. Some inferences about potential changes in stream salinity were made in Section 3.3 .4; the relatively small changes in hydrology were not expected to lead to significant changes in stream salinity at a regional scale. Climate change and land use

In comparing results under two different futures in this assessment, factors such as climate change and land use are held constant. Future assessment iterations could look to include these and other stressors to more fully predict cumulative impacts on a landscape scale. There is a relatively low density of meteorological stations in the subregion and to increase the level of predictability of rainfall estimates for rainfall-runoff modelling, it would be beneficial if additional rainfall gauges were installed in the mountain ranges along the eastern edge of the Gloucester subregion. While other meteorological variables would also benefit from being measured with enhanced spatial density, the overall gain would be minimal when compared to measuring rainfall with greater accuracy.

Last updated:
8 November 2018
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