Bedform maintenance and pool destratification by the new environmental flows on the snowy river downstream of the Jindabyne Dam, New South Wales

Wayne Erskine, Lisa Turner, Teresa Rose, Mike Saynor, Ashley Webb

    Research output: Contribution to journalArticle

    Abstract

    The hydrology, geomorphology and aquatic ecology of the Snowy River below the Snowy Mountains Hydroelectric Scheme were greatly altered by large-scale interbasin water transfers for power generation and the supply of water for irrigation until recent increases in environmental flow releases from Jindabyne Dam. Between 1967 and 2000 maximum releases from Jindabyne Dam were smaller than the lowest ever recorded mean daily discharge before flow regulation. The New South Wales and Victorian Governments agreed to return up to 28% of the natural mean annual flow to the river in keeping with recommendations from a community-sponsored Expert Panel. Detailed analyses of bedforms for 303 continuous km below the Scheme indicate that the new environmental flow regime will increase the pool-riffle spacing by between 3 and 294 m by increasing scour of pools and runs, and by reversing long-term channel contraction and pool infilling. Furthermore, strong thermal gradients and persistent oxygen stratification that produce bottom anoxia in upland pools will not develop under most environmental flows because of strong mixing. Even marked salt stratification in the upper estuary which can produce density differences of up to 14.9 kg/m3 between surface and bottom waters is unlikely to develop in future.

    Original languageEnglish
    Pages (from-to)152-171
    Number of pages20
    JournalJournal and Proceedings of the Royal Society of New South Wales
    Volume150
    Issue number2
    Publication statusPublished - 1 Dec 2017

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