3.5.1 Overview

This section describes the potential impacts on, and risks to, ecological, economic and sociocultural water-dependent assets from potential hydrological changes due to additional coal resource development. These were assessed using:

  • overlay analysis, whereby asset polygons (or lines or points) are intersected with a nominated zone of potential hydrological change to identify whether the asset is potentially subject to that hydrological change
  • qualitative mathematical models derived from expert elicitation
  • quantitative mathematical models (receptor impact models) derived from expert elicitation and based on the qualitative mathematical models.

As described in companion product 2.7 for the Hunter subregion (Hosack et al., 2018), receptor impact models were developed for two landscape classes in the ‘Riverine’ landscape group: permanent or perennial streams and lowly to highly intermittent streams, and for three landscape classes in the ‘GDE’ landscape group. Note that wet sclerophyll forests and dry sclerophyll forests have the same receptor impact model. Qualitative models were developed for other GDE landscape classes and for landscape classes in the ‘Coastal lakes and wetlands’ landscape group.

Overlay analysis was used to identify assets that are very unlikely to be impacted by surface water or groundwater changes due to additional coal resource development, based on lack of intersection of the asset with the zone of potential hydrological change. The zone of potential hydrological change is defined in Section 3.3. The impact and risk analysis uses different probabilities of hydrological change (5th, 50th (median) and 95th percentiles) to indicate the likelihood of hydrological changes to different types of water-dependent assets present in the zone. The 5th percentile identifies the magnitude of hydrological change that is very likely (greater than 95% chance); the 95th percentile defines the magnitude of hydrological change (though not necessarily ecological impact) that is very unlikely (less than 5% chance).

In this analysis of impacts and risks to water-dependent assets, ecological, economic and sociocultural assets are dealt with separately. Each subgroup of the ecological assets group is also described separately – ‘Surface water feature’, ‘Groundwater feature (subsurface)’ and ‘Vegetation’. To improve clarity, assets in the ‘Vegetation’ subgroup are further divided into two classes: ‘Groundwater-dependent ecosystems’ and ‘Habitat (potential species distribution)’. Economic assets are separated into two classes: ‘Groundwater management zone or area (surface area)’ and ‘Surface water management zone or area (surface area)’. Potential hydrological changes to all non-petroleum and gas bores in the zone of potential hydrological change are also considered. The intersection of sociocultural assets with the zone of potential hydrological change is then described, and the potential for impact assessed.

The spatial extent and number of water-dependent assets means that not all assets are mapped and assessed in this section. Instead the focus is on a subset of the assets, which are deemed to be ‘more at risk of hydrological changes’ (i.e. those assets associated with higher probabilities of larger hydrological changes). Detailed potential impacts on individual assets can be visually explored on the BA Explorer, available at www.bioregionalassessments.gov.au/explorer/HUN/assets.

The impact and risk analysis uses a combination of summary tables, maps of modelled hydrological change within assets, plots of cumulative asset extent and degree of modelled hydrological change and narrative. This section considers only the potential impacts on and risks to assets due to those mines in the coal resource development pathway (CRDP) that were modelled. Section 3.6 provides commentary on the potential impacts due to the CRDP mines that were not modelled.

Last updated:
15 March 2019
Thumbnail of the Hunter subregion

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