Changing water regimes and wetland habitat on the Lower Murrumbidgee Floodplain of the Murrumbidgee River in Arid Australia
Dr Richard Kingsford, April 2001
The project identified the following specific objectives:
- To determine effects of altered water regimes on wetland area in the Lowbidgee floodplain, at the confluence of the Murrumbidgee and Lachlan rivers, 1983-1998;
- To determine how water management has modified wetland habitat;
- To determine the impacts of wetland changes on species and abundance of waterbirds;
- To determine impact of changes to changes to wetland area in the Lowbidgee floodplain in the period 1983-1998;
- To analyse patterns of water flow to the Lowbidgee wetlands for a 50 year period using hydrological data from the Department of Land and Water Conservation in NSW; and
- To determine the impacts of changing water regimes, clearing and channelisation of wetland vegetation.
The project used long-term data to demonstrate the impact of change on the Lowbidgee Floodplain. The data collected was used to undertake a before/after/control/impact study.
It used satellite imagery (Landsat MSS Imagery) for the period 1975 to 1998 to determine the extent of wetland loss. Images were rectified to 1:100,000 maps and then classified initially on the basis of flooding using the software package Imagine (ESRI) for areas inundated and vegetated.
The extent of change was determined using GIS analyses ARCINFO (ESRI), followed by standard statistical analyses used to determine the significance of changes. Ground-truthing and aerial photography were used to validate and add to this information base. Historical maps added to the data by providing a long-term view of major system changes.
Waterbird abundance data exists for the Lowbidgee Floodplain (and other areas) from 1983 to 2000 in the form of aerial surveys. Waterbird counts were undertaken each October on wetland areas more than one hectare, along ten survey bands, thirty kilometres wide.
Other areas where data have been collected and where river management changes have not been undertaken provide control sites for the project. Three other sites where data have been collected on waterbird populations provided comparisons conditions to determine if changes were due to climate.
As different waterbirds feed on a number of different organisms, data was collected on up to fifty species to allow for an examination of which parts of the avifauna may have been most affected by changes occurring to the wetland community.
Breeding data provided information about the relationship between change and breeding of waterbirds in the area.
The impact of changing flows were examined upstream and downstream of the Lowbidgee through an analysis of trends set alongside other related impacts.
This project contributes considerably to on-ground management of the Lowbidgee Floodplain and the outcomes provide a sound scientific basis for management decisions about changes to water regimes and wetland habitat.
A copy of the final report is available from the National Parks & Wildlife Service web site .
Principal researcher's contact details:
Dr Richard Kingsford
NSW National Parks & Wildlife Service
PO Box 1967
HURSTVILLE NSW 2220
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