New Zealand Journal of Marine and Freshwater Research abstracts

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Critical depths for passage in braided rivers, Canterbury, New Zealand

M. PAUL MOSLEY

Ministry of Works and Development P.O. Box 1479 Christchurch, New Zealand

Abstract Riffles and points of divergence of branch channels in braided rivers are critical controls upon passage of fish and recreational boats because they are points at which depths are at a minimum. Depths on randomly selected riffles were measured in braided reaches of the Ashley, Hurunui, and Rakaia Rivers and related to discharge; minimum depths encountered in extended reaches of these rivers at a range of flows have also been measured. The data can be used to predict minimum available passage depths at a specified flow, or conversely, to predict the discharge required to maintain a specified minimum passage depth. However, presently available estimates of critical minimum depths required for various instream uses (migration of salmonids, jetboating) appear excessively conservative, and minimum depth requirements must be more accurately determined before instream flow needs can be properly assessed.

Keywords rivers; stream flow; fluvial morphology; water resources; recreational waters; fish; boats; Canterbury.

New Zealand Journal of Marine and Freshwater Research, 1982, Vol. 16 : 351-357 Received 2 July 1982; accepted 23 August 1982

PDF file of entire paper: medium quality (1234K); (scanned from paper original: notes about this process)

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