Impact of logging in the Gellibrand catchment.
Greater Arkins creek catchment
Research by Sinclair Knight Merz (SKM) released last year investigated
three scenarios regarding forest management within the Greater Arkins
Catchment area (1100 ha) which is an important high rainfall component
of the Gellibrand water supply catchment.
The net loss in water yield attributed to logging in the Greater Arkins Catchment is about 17% or 650 ML a year.
There is an estimated 17,000 ha of high rainfall forest on public land available for clearfell logging on the southern side of the Gellibrand catchment. If it was assumed that this entire area behaved similar to the Greater Arkins Catchment and ignore logging in lower rainfall areas, there would be at least an annual 10,000 ML of extra water running off into the Gellibrand river within 60 years if clearfell logging on public land was stopped now.
If a large fire burnt out a significant component of the native forest in the high rainfall areas of the Gellibrand catchment, considerable social and economic stress will occur as water yield began to decrease in the summer months. There could be considerable political pressure to construct more dams in the Gellibrand catchment as a means of improving water supply reliability at a cost of hundreds of millions. Proposals to build new dams could result in the flooding of agricultural land in the Gellibrand and disrupt environmental flows.
No logging and no fire will increase summer flows