Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/33992

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Title
Spatial and temporal variations in bank erosion on sand-bed streams in the seasonally wet tropics of northern Australia
Author/Creator
Saynor, M. J.;  Erskine, Wayne D.
Institution
The University of Newcastle. Faculty of Education & Arts, Wollotuka School of Aboriginal Studies
Description
Bank erosion rates and processes across a range of spatial scales are poorly understood in most environments, especially in the seasonally wet tropics of northern Australia where sediment yields are among global minima. A total of 177 erosion pins was installed at 45 sites on four sand-bed streams (Tributaries North and Central, East Tributary and Ngarradj) in the Ngarradj catchment in the Alligator Rivers Region. Bank erosion was measured for up to 3·5 years (start of 1998/99 wet season to end of 2001/02 wet season) at three spatial scales, namely a discontinuous gully (0·6 km²) that was initiated by erosion of a grass swale between 1975 and 1981, a small continuous channel (2·5 km²) on an alluvial fan that was formed by incision of a formerly discontinuous channel between 1964 and 1978, and three medium-sized, continuous channels (8·5-43·6 km²) with riparian vegetation. The bank erosion measurements during a period of average to above-average rainfall established that substantial bank erosion occurred during the wet season on the two smaller channels by rapid lateral migration (Tributary Central) and by erosion of gully sidewalls due to a combination of within-gully flows and overland flow plunging over the sidewalls (Tributary North). Minor bank erosion also occurred during the dry season by faunal activity, by desiccation and loss of cohesion of the sandy bank sediments and by dry flow processes. The larger channels with riparian vegetation (East Tributary and Ngarradj) did not generate significant amounts of sediment by bank erosion. Deposition (i.e. negative pin values) was locally significant at all scales. Bank profile form and channel planform exert a strong control on erosion rates during the wet season but not during the dry season.
Relation
Earth Surface Processes and Landforms Vol. 31, Issue 9, p. 1080-1099
Publisher Link
http://dx.doi.org/10.1002/esp.1310
Date
2006
Publisher
John Wiley
Keyword(s)
erosion pins;  process dominance zones;  deposition;  bank profile form;  channel planform
Resource Type
journal article
Identifier
http://hdl.handle.net/1959.13/33992
Identifier
ISSN:1096-9837
Reviewed
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Subject
"Earth Surface Processes and Landforms"
 
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