Inter-Basin-Water Transfers significantly reduce flow and sediment regimes to the
downstream ecosystem effecting differential channel adjustment at various locations. It
is not known how macroinvertebrates adjust to flow regulation, either spatially or
temporally, because research is lacking into how morphological adjustment affects
benthic habitat. Feedback mechanisms that initiate the adjustment process must first be
identified, then the effect on benthic habitat becomes apparent, thus, providing a link to
macroinvertebrate response.
Since regulation there has been a 95% reduction in flow volume, a complete downward
shift in both the flow duration and flood frequency curves and a 194% increase in flow
constancy compared to the pre- dam period. Furthermore, Jindabyne Dam traps 99.9%
of the total incoming sediment load.
Upstream of the tributary the dominant river response was accommodation adjustment
with subsequent contraction of the river channel. Associated feedback mechanisms
were ?armouring? and vegetation encroachment. Downstream of the tributary response
was more complex, with channel contraction through aggradation and specifically the
formation of a tributary mouth bar and fan, mid channel lobate bar, transverse bar and
in-channel bench. Associated feedback mechanisms were interactions between
vegetation and sediment; channel morphology, flow and sediment distribution; and
sediment distribution, flow and channel morphology. These processes have had site
specific and reach scale impacts on benthic habitat.
Macroinvertebrate response to flow regulation was habitat specific (riffle or edge) and
seemed to correspond to either site, or reach scale morphological adjustment, whereas,
flow constancy seemed to affect edge macroinvertebrates throughout both reaches.
Spatially, macroinvertebrates have not adjusted to the post- dam flow regime and
temporally, macroinvertebrates have not recovered 30 years after the closure of
Jindabyne Dam. How physical processes change habitats and how these impact on a
river?s ecology and at what scale, are important considerations in river management.
| Identifer | oai:union.ndltd.org:ADTP/201041 |
| Date | January 1999 |
| Creators | Rose, Teresa, n/a |
| Publisher | University of Canberra. Cooperative Research Centre for Freshwater Ecology |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright Teresa Rose |
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