The effect of river regulation on floodplain wetland inundation, Murrumbidgee River, Australia
Paul Frazier A C and Ken Page BA Ecosystem Management, Centre for Spatial Sciences, University of New England, Armidale, NSW 2351, Australia.
B School of Science and Technology, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.
C Corresponding author. Email: pfrazier@une.edu.au
Marine and Freshwater Research 57(2) 133-141 https://doi.org/10.1071/MF05089
Submitted: 16 May 2005 Accepted: 3 November 2005 Published: 2 February 2006
Abstract
River regulation by headwater dams has altered the flow regime of rivers worldwide. For floodplain rivers, reduced connectivity between the main channel and floodplain wetlands has led to a decline in ecological health. Current river restoration theory advocates a return towards a more natural regime of floodplain wetland inundation. However, for many rivers, a poor understanding of the natural floodplain wetland inundation regime has hampered effective restoration management. This paper describes a technique for quantifying the effect of flow regulation on the inundation regime of floodplain wetlands on an extended reach of the Murrumbidgee River, Australia. A series of Landsat Thematic Mapper (TM) images, captured before and after a set of floods, was analysed to describe the relationship between flow and inundation for a 640 km river reach. These data were combined with historical regulated and modelled natural daily flow data to show that river regulation has reduced the duration and frequency of wetland inundation by ~40%. For the majority of wetlands the capture of small and medium floods in the headwater dams reduced wetland inundation substantially. However, for low connecting wetlands in reaches upstream of the main irrigation off-takes, summer irrigation flows have increased inundation.
Extra keywords: integrated quantity quality model, IQQM, Landsat Thematic Mapper, modelled natural flow, remote sensing.
Acknowledgments
We thank John Louis and Sue Briggs for comments and advice on project design and presentation; the NSW Department of Infrastructure Planning and Natural Resources for partly funding the project and providing IQQM and rating table data for the Murrumbidgee River; and Darren Ryder for reviewing the manuscript.
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