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Evaluating the impact of the Wimmera Mallee Pipeline on biodiversity on farms
by Jonathan Starks
February 2007
RIRDC Publication No 07/037 RIRDC Project No BCG?2A
Executive Summary
What the report is about
Piping will increasingly
replace open channels for rural water delivery. While increasing water
efficiency, piping can reduce access to wildlife. We need to understand
and manage these effects.
This report focuses on and explores the aspects and impacts of the Wimmera Mallee Pipeline on existing wildlife and biodiversity in the region.
Who the report is targeted
at
Decision makers and land
managers who are involved in piping rural water supplies. The findings
in this report will aid decision makers regarding water management on their
lands as well as raising awareness of the importance of preserving wildlife
diversity on their properties.
Background
The Wimmera Mallee Pipeline
will replace an extensive network of gravity-fed earthen channels and farm
dams with a closed water system of pipes and stock troughs. A diverse array
of wildlife relies on farm dams and channels as their water supply. Changing
the availability of open water will have an impact on the diversity and
abundance of wildlife in the region. Understanding the existing wildlife
values on farms of the different water delivery systems is necessary for
the maintenance and improvement of biodiversity, habitat function and community
well-being.
Objectives
The main objectives of this
project are to assess the biodiversity values of stock water points in
the Wimmera Mallee Channel/dam region and the Northern Mallee Pipeline
region, to determine whether biodiversity and habitat function can be maintained
in a farming landscape through the strategic use of purpose-built water
points for wildlife, to investigate the costs involved in installing and
maintaining such wildlife water points, and to develop guidelines for farmers
and industry on the use of water points for wildlife for best environmental
benefit within a piped water delivery system.
Methods
Thirty six study sites were
chosen to assess the biodiversity value of farm dams, channels, stock troughs,
open paddocks and woodlands. An experimental water trough for wildlife,
comprising an inground concrete trough with a sloping floor, holding 6000
litres of water and planted with aquatic vegetation was also trialled.
Surveys sampled birds, mammals, reptiles and frogs at each of the study
sites.
Results and key findings
This study found that biodiversity
levels on farms were higher at sites with open water and at sites in woodlands.
Birds provided the best indicators of the relative biodiversity values
of the different study sites. Wildlife water troughs, as measured by bird
populations, can increase the biodiversity value of a woodland area and,
significantly, maintain biodiversity values at levels comparable with farm
dams in woodlands.
The faunal group likely to be most seriously affected by the loss of open water are frogs and the Common Long-necked Turtle. This group was found at sites in the Wimmera Mallee Channel/dam region but not at sites in the Northern Mallee Pipeline region. The wildlife water troughs did not prove effective in attracting frogs and turtles, though this may be due to the sites chosen for the wildlife water troughs and the relatively short time the troughs have been functioning.
Implications
The application of wildlife
water troughs in a farming landscape can increase biodiversity levels,
as measured by birds, in the Northern Mallee Pipeline region, and maintain
existing biodiversity values in woodlands within the Wimmera Mallee Channel/dam
region. Frogs, turtles, and possibly bats, will be seriously disadvantaged
by the loss of open water following decommissioning of channels and dams.
Wildlife water troughs can be an efficient and cost-effective way of maintaining and enhancing wildlife values on farms in the Wimmera and Mallee within a piped water delivery system.
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