Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/919523

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Title
Natural river recovery from catastrophic channel changes by vegetation invasion of the sand-bedded Wollombi Brook, Australia
Author/Creator
Erskine, Wayne D.;  Chalmers, Anita
Institution
The University of Newcastle. Faculty of Science & Information Technology, School of Environmental and Life Sciences
Description
Catastrophic channel changes on Wollombi Brook were initiated in June 1949 by a flood with a peak discharge more than 38 times greater than the mean annual flood. Subsequent large floods between 1950 and 1952 extended the changes initiated by the 1949 flood. By the end of 1952, the channel had widened by about 100% and at least 4 m of sand had been stored in the bed. Hydraulic changes caused by these floods resulted in a reduced capacity to transport this stored sand. Slow bed degradation and channel contraction by the development of marginal benches resulted in partial river recovery. However, the measured rates of degradation and channel contraction would take about 100 years for the channel to return to its pre-1949 dimensions, which is less than the calculated recurrence interval of the 1949 flood (170 yrs on the annual maximum series). Wollombi Brook had been an active sand-bed stream since at least 1819 when it was first discovered by Europeans. However, since 1995, the trajectory of river recovery has changed dramatically from that before 1995. Vegetation colonisation of the bed has anchored the stored sand producing a hydraulic geometry not found during the previous operation of the longest operating gauging station (1908 to present). Twelve years of vegetation establishment resulted in the plants surviving a catastrophic flood in June 2007, a situation which had not occurred during the previous 188 years. Although Wollombi Brook is one of the most flood variable rivers in the world, vegetation has been able to stabilize the sand substrate and marginal benches.
Relation
7th International Symposium on Ecohydraulics. The 7th International Symposium on Ecohydraulics: The International Conference of Science and Information Technologies for Sustainable Management of Aquatic Ecosystems (Concepción, Chile 12-16 January, 2009)
Relation
http://www.udec.cl/pexternoe
Date
2009
Publisher
University of Concepción
Keyword(s)
Wollombi Brook (N.S.W.);  river recovery;  floods;  channel changes;  vegetation
Resource Type
conference paper
Identifier
http://hdl.handle.net/1959.13/919523
Identifier
ISBN:9789810821005
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Subject
"Natural river recovery from catastrophic channel changes by vegetation invasion of the sand-bedded Wollombi Brook, Australia"
 
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