Bulletin

Issue: May 2004

Environment

Water sleuth seeks solutions

There is controversy over water resource allocation and value-for-money associated with existing and proposed environmental works.

How effective are current methods of rehabilitating wetlands of the Murray and other rivers in the Murray-Darling Basin?

Aaron Troy, a La Trobe University Albury-Wodonga wetland ecologist, will literally get his hands both dirty and wet over the next two years in a very practical search for the answer to this question.

Mr Troy will analyse the effects the North East Catchment Management Authority?s (NECMA) structural rehabilitation techniques such as earthworks, channels and regulators have on the relative health of the wetlands using such indicators as water, soil, plants, fish and insects.

He will examine six such planned sites between the Hume Weir and the Barmah Forest for one year before the works are carried out, and for a further year after they have been completed.

In his second year of his PhD and conducting the research for his thesis, Mr Troy will compare findings from each of the six ?human-influenced? sites with six floodplain sites that remain unchanged in their current hydrological regime.

He will collect macro-invertebrates ? dragon flies, backswimmers (water boatmen), water beetles and other insects; macrophytes ? aquatic plants such as reeds and water grasses; and also catch fish species such as Murray cod, carp smelt and gudgeons.

In addition he will examine water quality, including salinity and nutrients (nitrate and phosphorus) and the total carbon, nitrogen and phosphorus contents of soil in the wetlands

Explaining the need for such research, Mr Troy said that catchment management authorities have allocated significant resources for earthworks and regulation construction in attempts to rehabilitate floodplain wetlands.

?These floodplain wetlands have reversed seasonal flooding and drying regimes which the NECMA intend to return to a near natural regime. These altered flood regimes, caused by river regulation primarily for irrigated agriculture, are blamed as being the main determinant in affecting wetland health and productivity in the mid-Murray,? he said.

?Large environmental water allocations and works programs are now being employed in an attempt to rehabilitate wetland health, with substantially larger efforts proposed. However, there is controversy over water resource allocation and value-for-money associated with these environmental works.

?This is because usually only anecdotal evidence and isolated monitoring programs exist to support the need for such works. However none have fully quantified the outcomes of such programs.

?My study will incorporate multiple control and impact sites which will increase the capacity to distinguish between differences due to human impact ? non-seasonal flows ? and those due to natural changes.

?The project will provide statistically valid quantification of the results of the rehabilitation works, and determine their value for money. My research will provide valid scientific data which can be used when future decisions are made about such programs,? Mr Troy said.

He will work with his two PhD supervisors, Dr Phil Suter and Adjunct Professor Terry Hillman of La Trobe University Albury-Wodonga, Mr Keith Ward, NECMA wetlands manager and two scientists from the Arthur Rylah Institute, Mr John Koehn and Mr Jason Lieschke.

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