In 1971/72 Picaninny Creek catchment was substantially clear- felled and regenerated, predominantly with mountain ash.
The annual flow increased for the next three years (relative to the control), reaching a peak of almost 300 mm increase relative to the control catchment.
Flow then declined; eight years after the logging the annual flow had returned to pre-logging levels. The flow then continued to decline with a maximum reduction of around 200 mm per annum.
Thirty-four years after logging the flow was still below the pre-treatment flow and showing no sign of recovery, although there were year to year variations associated with rainfall and drought.
In 1972/73 Blue Jacket Creek had a “sawmiller selection” cutting in which approximately 50% of the basal area was removed. The response was a similar but muted version of the Picaninny response. Comparison of the results of change of flow in Picaninny Creek with models of ash and mixed species used showed that these models substantially and consistently over-estimated the magnitude of the change.
The models generally predicted that Picaninny Creek should have dried up completely a one or two years after logging. Picanniny Creek flow has diminished but to a far lesser extent than predicted by these commonly-used models. The results from Coranderrk are compared with published data from other long term paired watershed studies in similar forest types with particular regard to the “catchment efficiency” – the ratio of water entering to water leaving the catchment.
The seminar will conclude with discussion on what might be viewed as an “acceptable” catchment efficiency, and whether future generations will demand more runoff from these catchments than has historically been produced under either old growth or regrowth vegetation.
Date: 27th January 2009
Time:1:00 – 2:00pm
Location:Room 5.3, Level 5, VECCI, Albert Street, East Melbourne, Melways 2F K1
RSVP:By Thursday 22nd January
To: Katherine [email protected]
03 5321 4321