Title of article :
Modern depositional processes in a confined, flood-prone setting: Benches on the Shoalhaven River, NSW, Australia
Author/Authors :
Kermode، نويسنده , , S.J. and Cohen، نويسنده , , T.J. and Reinfelds، نويسنده , , I.V. and Jones، نويسنده , , B.G.، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2015
Pages :
16
From page :
470
To page :
485
Abstract :
Past research has suggested that in-channel alluvial landforms, often termed benches, are associated with flow events with specific return periods and that such landforms are inset within terraces, floodplains, or higher bench surfaces. Chronostratigraphic analysis and hydraulic modelling in a bedrock-confined reach of the lower Shoalhaven River show that they have been extensively eroded and at least partially reformed during the historical period. Lower benches are inundated by flood events with average recurrence intervals (ARI) of 2 or less years, middle benches by events ca. 5 years ARI, and upper benches by events ca. 10 years ARI. The lower benches commonly share over- or onlapping stratigraphic units, demonstrating that deposition can occur on multiple bench surfaces simultaneously. This is in contrast to earlier suggestions of discrete bench surfaces being associated with, and formed by, events that have a specific return period. In the Shoalhaven River, Pleistocene and Holocene terraces determine the large alluvial channel geometry for a wide range of discharges up to the 50-year return interval with benches forming temporary sediment storages within this larger channel. The large channel dimensions and associated hydraulics and high annual flood variability (flash flood magnitude index of 0.53) for the Shoalhaven River facilitate the construction of multiple bench surfaces across a range of elevations. Benches are formed of a wide range of facies from decimetre-thick massive sand units through interbedded sands and silts.
Keywords :
Bench stratigraphy , inundation frequency , Compound benches , Sediment storage , Flow variability
Journal title :
Geomorphology
Serial Year :
2015
Journal title :
Geomorphology
Record number :
2367578
Link To Document :
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