Surface water

As part of the Assessment, an analysis was carried out to assess streamflow in the Richmond river basin (McJannet et al., 2015). Major streams within the Richmond river basin, their median daily flow volumes (based on flow duration curves), their spatial relationships to the potential CSG development area and tidal river reaches are shown on Figure 27. Findings of the streamflow analysis included:

  • The main tributary of the Richmond river basin has a tidal influence just downstream of the Casino gauging station (river course distance of 114 km from the ocean), whereas the Wilsons River tributary is tidal at Lismore (river course distance of 115 km from the ocean) and further upstream (Figure 27). Due to this tidal influence, the flow of the Richmond River downstream of Casino is less likely to be influenced by extractions or discharge associated with potential CSG developments.
  • The Richmond River at Casino is perennial and has a long-term median flow of 320 ML/day.
  • The south-west part of the Richmond river basin has relatively low median daily flows, with Shannon Brook (28 ML/day) and Myrtle Creek (9 ML/day) both near-permanent, flowing on average 93% and 94% of the time, respectively. The potential CSG development area underlies part of the catchment of Shannon Brook.

Figure 27

Figure 27 Major streams in the Richmond river basin and tidal river reaches; median daily streamflow rates (in ML/day) at gauging sites are also shown

Data: Bioregional Assessment Programme (Dataset 3, Dataset 4, Dataset 5, Dataset 11)

Most of the gauged streams are perennial, with the exception of Shannon Brook and Myrtle Creek, which are located in the southern part of the basin. Those two near-permanent streams have median flows that are much lower than their counterparts in the northern part of the basin.

The boundary of the surface water PAE, which takes into account locations of all current and future CSG developments, provides the extent to which effects of any possible future development can potentially occur.

Current surface water license allocations in the Richmond river basin are 99,881 ML/year (McJannet et al., 2015). These allocations are concentrated along the main river valleys of the Richmond River and major tributaries such as Eden Creek, as well as in the Wilsons River basin and the Alstonville Plateau in the east of the Richmond river basin (Figure 28). Location of catchment boundaries and inflow to and outflow from the Richmond river basin

Any outflows from the potential CSG development areas are contained within the Richmond river basin. The surface water analysis for the Clarence-Moreton bioregion is restricted to the Richmond river basin, as this is the only river basin with an additional coal resource development. However, the underlying groundwater model extends further west into the upper Clarence river basin to capture the wider recharge area of the Walloon Coal Measures, which extend beyond the surface catchment boundary.

The rainfall-runoff model (AWRA-L) has been chosen to model the surface water system. Further information on surface water modelling in the Clarence-Moreton bioregion is available in companion product 2.6.1 (Gilfedder et al., 2016).

Figure 28

Figure 28 Current surface water permits in the Richmond river basin (based on McJannet et al., 2015)

Data: Bioregional Assessment Programme (Dataset 3, Dataset 4, Dataset 5, Dataset 12)

Last updated:
5 March 2019
Thumbnail images of the Clarence-Moreton bioregion

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