3.7.2 Future monitoring

Post-assessment monitoring is important to test and validate (or invalidate) the risk predictions of the assessment. At the highest level, hydrological and ecological monitoring effort should reflect the risk predictions, and focus the effort where the changes are expected to be the largest and incorporate those areas where modelling limitations did not allow the risk to be quantified. However, it is also important to place some monitoring effort at locations with lower risk predictions or where no impacts are expected (as control sites) so as to confirm the range of potential impacts, identify any unexpected outcomes, and provide baseline information to assist any future assessment of other developments (e.g. any of the developments included in the CRDP that could not be quantitatively assessed for this BA, as discussed in Section 3.6).

The BA for the Galilee subregion has identified that potential hydrological or ecosystem impacts are likely in areas concentrated around the locations of the seven proposed coal mines in the CRDP that were modelled in this BA (as outlined in the qualitative assessment in Section 3.6, the other seven coal mines and three CSG developments in the CRDP were unable to be modelled due to lack of relevant information when the models were being developed). Groundwater monitoring effort should concentrate on the discrete drawdown zones identified in the hydrological modelling, particularly focusing on areas where gaps may exist in the current monitoring bore network for individual mines or near key assets. For instance, monitoring bores targeting confined parts of the Clematis Group aquifer and Dunda beds, up-hydraulic gradient (particularly to the west and south) of the discharge springs in the Doongmabulla Springs complex, would provide additional information around variations in groundwater pressures and hydrochemistry in what may be a significant source aquifer these springs. Monitoring of the unconfined Cenozoic aquifers in key areas of the Belyando River floodplain would assist in determining the degree of near-surface drawdown and potential connectivity with deeper aquifers. An important location for monitoring groundwater changes in the Cenozoic alluvial aquifer is the area around Alpha township where the regional groundwater AEM could not rule out potential impacts nor quantify any such changes. Targeted monitoring efforts could include installation of nested piezometers at key sites where drawdown impacts are predicted to affect multiple stacked aquifers, so that water levels could be monitored to better understand potential fluxes between aquifers, as well as with the surface water network. Future surface water monitoring efforts would be best targeted along suitable reaches of Native Companion, North, Sandy, Alpha, and Tallarenha creeks, and the Belyando and Carmichael rivers, where the BA modelling results indicate the most substantial changes across the spectrum of the low-flow, high-flow and annual flow regime.

While the main focus of monitoring efforts should be on areas in the zone of potential hydrological change, it is also appropriate to consider monitoring of groundwater and surface water near important assets that may occur just outside the zone (e.g. any key assets within about 10 km of the zone boundary). This is because it is plausible that the regional-scale hydrological modelling for this BA may not necessarily be able to predict local-scale variations that may influence groundwater systems near the margins of the zone. Likewise, there is also merit in considering possible hydrological and ecological monitoring options for the broader suite of developments in the CRDP (i.e. those mines and CSG projects that could not be modelled in this BA). As these future developments occur in several discrete areas away from the zone of potential hydrological change defined in this assessment (see Section 3.6), establishing a well-planned monitoring network prior to the start of operations in these areas could provide important biophysical data that could be used to better understand the environmental baseline within and around these planned sites of coal resource development. Ideally, such pre-development monitoring should start well in advance of mining operations (i.e. at least 5 to 10 years), so as to maximise the temporal extent of baseline data collection prior to extraction.

Besides future targeted monitoring points outlined in the previous paragraphs, a number of gaps and limitations identified in Section 3.7.4 would benefit from consistent and regular data collection. Filling some of these data gaps would improve the risk quantification component of this Assessment. This includes surface water and ecological baseline data collection to improve the understanding of environmental conditions and parameters, including those related to surface water and groundwater quality. In particular, the collection of such information prior to the onset of development activities, as well as ongoing through the early stages of mine construction and production, would enhance the baseline understanding of important ecosystems within the zone and help to track any potential responses due to the additional coal resource development.

The availability of ecological monitoring data for benchmarking, including identifying current conditions, and comparing and identifying changes in ecosystems and ecosystem indicators, is very limited, especially for dealing with regional-level changes. There is a lack of ecohydrological understanding around the water requirements for the many water-dependent vegetation communities, and how these relate to specific hydrological response variables – a crucial requirement for assessing impacts related to hydrological changes. Consequently, future investigations and coordinated monitoring to address such knowledge shortcomings would strengthen any further assessment of cumulative impacts due to coal resource development in the Galilee Basin, including those developments in the CRDP that could not be assessed by the hydrological modelling in this BA (as outlined in Section 3.6).

In mid-2017, following consultation with the Assessment team, an airborne electromagnetics survey (a type of geophysical survey technique) was flown over select parts of the Galilee subregion by Geoscience Australia. The main objective of this survey was to determine whether this method could be used to cost-effectively detect a variety of near-surface geological structures (i.e. such as geological faults and other structural features within about 200 m of the land surface) in a range of landscape and geological settings in the Eromanga and Galilee basins. Another aim was to refine the conceptualisation of groundwater dynamics in the Galilee and Eromanga basins. Target areas for collection of electromagnetics data included the Doongmabulla and Edgbaston spring complexes, the lakes Galilee and Buchanan, Cenozoic sediment deposits in the Belyando River valley, GAB aquifer recharge beds in the Eromanga Basin, and faulting associated with the western margin of the Galilee subregion. These airborne electromagnetics data and interpretations will be released in coming years as they become available over the course of Geoscience Australia’s investigations for Exploring for the Future (Geoscience Australia, 2017). These data could be used to inform location of future monitoring bores through the improved understanding of the role of geological structure and architecture as a controlling factor on groundwater hydrodynamics, particularly in near-surface aquifers.