New Zealand Journal of Marine and Freshwater Research abstracts

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Harbour entrance morphology and sediments at a river mouth port, Westport, New Zealand

R. M. KIRK W. J. HASTIE J. L. LUMSDEN

Department of Geography University of Canterbury Private Bag, Christchurch New Zealand
R. W. Morris and Associates Consulting Engineers Limited P. O. Box 4189, New Plymouth New Zealand
R. W. Morris and Associates Consulting Engineers Limited P. O. Box 8074, Christchurch
New Zealand Abstract Entrance morphologies and sediment characteristics were studied at Westport Harbour, a river mouth port located on the Buller River, New Zealand. The most frequent morphology found was that in which two submarine bars were present off the river mouth. When present, these bars were separated by a transverse channel running east from Carters Beach and terminating in the principal inlet channel. Sediment samples were collected and analysed for grain size, reliability (grain shape), and, in a few instances, mineralogy. The data collected suggested that longshore sediment transport is predominantly west to east and that river derived sediment is deflected to the east. The inner bar is predominantly a littoral drift related event whereas the outer bar, which is composed mainly of littoral drifted sediment, forms as a submarine extension of Carters Beach. Both bars can be modified by floods in the river, although modification of the outer bar is much less frequent because of the very high river flows required. Sediment can bypass directly across the river mouth only when the inner bar is present. On other occasions bypassing can only occur by transport through the transverse channel or over the outer bar, into the river channel and then onshore.

Keywords Westport; river mouth port; river mouth bars; sediment analysis; sediment transport; grain size; grain shape; reliability; mineralogy

New Zealand Journal of Marine and Freshwater Research, 1986, Vol. 20 : 689-697 Received 25 November 1985; accepted 21 March 1986

PDF file of entire paper: medium quality (682K); (scanned from paper original: notes about this process)

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