2.5.2 The water balances

Summary

The surface water balance analysis is reported at four model nodes: the Richmond River above Casino, the Richmond River above Kyogle, Shannon Brook above Yorklea and Eden Creek. It is reported for three consecutive 30-year periods, each with different rainfall inputs to reflect modelled varying climate signal. The median change at all four model nodes was essentially zero (less than 0.05 GL total) in surface water balance for each of the 30-year periods (2013 to 2042, 2043 to 2072 and 2073 to 2102). There are insignificant changes in baseflow during the three 30-year periods.

Based on the current groundwater model conceptualisation, groundwater storage exhibits a future decline even without the impacts of the West Casino Gas Project, although the median annual reduction is well below 0.5% of the corresponding median annual recharge for all the three reporting periods. This can be a result of climate change, extraction for irrigation and other usage. Water usage by the West Casino Gas Project mainly occurs between 2013 and 2042 with a median mean annual pumping of 328 ML/year. An additional 321 ML/year reduction in groundwater storage occurs due to the West Casino Gas Project from 2013 to 2042. A very small impact is also seen in the discharge component to surface water to compensate for coal seam gas (CSG) water production. No other impact can be identified for the other water balance components.

Last updated:
11 July 2017