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The role of flooding in morphological changes in the regulated Lower Ord River in tropical northwestern Australia
Author(s) -
Cluett Lisa
Publication year - 2005
Publication title -
river research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.679
H-Index - 94
eISSN - 1535-1467
pISSN - 1535-1459
DOI - 10.1002/rra.842
Subject(s) - ephemeral key , flooding (psychology) , hydrology (agriculture) , flood myth , channel (broadcasting) , vegetation (pathology) , geology , floodplain , environmental science , geography , ecology , archaeology , medicine , psychology , geotechnical engineering , cartography , engineering , pathology , electrical engineering , psychotherapist , biology
The discharge of the Lower Ord River has been regulated since 1972 when a second dam was built on this major river system. This previously ephemeral river, punctuated by peak wet season flows, is now characterized by permanent, regulated flows all year, and complex adjustments to the downstream channel morphology are evident. Geographic Information System techniques, combined with field surveys, reveal a series of interrelated adjustments in response to recent flooding. These include sedimentation, channel narrowing and vegetation encroachment, all of which have implications for sustainable management and are issues that have been managed by flushing flows in other rivers. The largest flood events since regulation occurred some 27 years after dam construction during consecutive wet seasons. These events have prompted an examination of the potential to ‚flush’ the post‐regulation Lower Ord channel to modify some of the channel changes that occurred in response to dam construction. A detailed geomorphic investigation of the Lower Ord river showed that that some of the features formed under low flows have been eradicated (partly or completely) by these large flood events, while others have withstood them. The modification of changes since dam construction varies according to a range of factors including reach position, extent of vegetation cover and local morphological variation. It is clear, however, that features not removed during floods may be considered quasi‐permanent, and therefore are likely to play an important role in the evolution of this regulated river. Copyright © 2005 John Wiley & Sons, Ltd.