Catchment issues | Environment Victoria

Catchment issues

Rebalancing between environmental and consumptive use is a formidable challenge under the climate change scenarios. However it is important to remember that rainfall is not the only determinant of water availability in the catchment.

Catchment management is a highly significant influence and interception activities, such as farm dams for stock and domestic use, timber plantations and deep rooted crops, can have considerable impact on inflows into creeks and river systems. As inflows decline, a greater proportion of the available water is captured by these activities and their impact on river flows and downstream users increases. These activities currently sit outside the water allocation framework and are not regulated. Their inclusion and regulation under the Water Act is a matter of urgency, particularly in catchments like the Campaspe where in recent years over 30% of inflows are captured by unlicensed farm dams. (18)

Bushfires, reafforestation and logging have been identified as other threats to shared water resources. Millions of hectares of the major water supply catchments of the Murray, Goulburn and Ovens systems have been burnt out in recent years, which will have a severe impact on future inflows.

A recent study shows that an immediate cessation of logging in the Goulburn catchment would add an extra 20GL/year to inflows by 2050 and 163GL/year by 2150. (19) Net present value analysis shows that the additional water yield delivered over the next 100 year period has a value of $1.68 billion. In addition, the study shows that over $6 billion worth of stored carbon and increased bushfire resilience benefits would result. These multiple benefits are hard to ignore.

Groundwater is being increasingly used as a substitute for surface water but this is not necessarily a long-term option as groundwater recharge is ultimately dependent on rainfall and will decline in a drier climate. Groundwater also provides base flows to many rivers which will become an increasingly important contribution as surface inflows decline.

Question for discussion:

What are the priorities for river health in northern Victoria?

References

(18) Draft NRSWS p165

(19) Australian Conservation Foundation (2009) Woodchipping our Water: A case for reassessing the use of Victoria’s Goulburn catchment’s wet montane forests