Point bar and floodplain formation of the meandering Beatton River, northeastern British Columbia, Canada

Sedimentology - Tập 27 Số 1 - Trang 3-29 - 1980
Gerald C. Nanson1
1Department of Geography, The University of Wollongong, Wollongong, N.S.W. 2500 Australia

Tóm tắt

ABSTRACTThis study examines the morphology, sedimentology and genesis of the point bars and floodplain of the Beatton River. The formation of point bars occurs in distinct stages. An initial point bar platform composed mainly of coarse sediment is formed adjacent to the convex bank of a migrating meander bend, and is the base on which develops a single scroll bar of fine traction and suspended load. With continued sedimentation, the scroll bar grows, eventually supporting vegetation and becoming a floodplain ridge. Scroll bars form with greatest size and frequency in rapidly migrating bends, and the shape of the meander bend appears to determine both the location of the initial bar deposit, and its direction of growth up or downstream. Approximately one‐half of the floodplain sediment is derived from suspended load, and the initiation of a scroll bar appears to be due to excessive deposition of suspended load in a zone of flow separation over a point bar platform. The critical flow condition for the initiation of a scroll bar does not occur with the same recurrence interval on different shaped meander bends, however, the average recurrence interval within the study reach is approximately every 30 years. Sedimentation rates on point bars and on the floodplain indicate two relatively distinct stages of floodplain alluviation. The most rapid is for surfaces less than 50 years old, although sediment accumulation still persists on surfaces up to 250 years in age. Although frequently flooded, surfaces older than this accumulate very little sediment. Despite 2–3 m of overbank deposition, the amplitude of floodplain ridges is maintained by secondary currents which sweep sediment from the swales towards the ridge crests.

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Tài liệu tham khảo

10.2475/ajs.270.5.361

10.1111/j.1365-3091.1965.tb01561.x

10.1111/j.1365-3091.1966.tb01576.x

Allen J.R.L., 1968, Current Ripples

Allen J.R.L., 1970, Studies in fluviatile sedimentation: a comparison of fining‐upward cyclothems, with special reference to coarse‐member composition and interpretation, J. sedim. Petrol, 40, 298

10.1002/gj.3350070108

Bagnold R.A., 1954, The Physics of Blown Sand and Desert Dunes

Bagnold R.A., 1960, Some aspects of river meanders, Prof. Pap. U.S. geol. Surv, 282

10.1144/sjg07020093

10.1111/j.1365-3091.1975.tb00282.x

10.2110/pec.65.08.0133

10.1086/627156

10.2475/ajs.266.6.417

Fisk H.N., 1944, Geological investigation of the alluvial valley of the Lower Mississippi River

Fisk H.N., 1947, Fine‐grained alluvial deposits and their effects on the Mississippi River activity

10.1306/74D70646-2B21-11D7-8648000102C1865D

Happ S.C, 1940, Some principles of accelerated stream and valley sedimentation, U.S. Dept. Agric. Tech. Bull., 695

10.2475/ajs.274.4.414

10.1139/e78-191

10.1130/0016-7606(1975)86<487:TCOCMO>2.0.CO;2

10.1086/628140

Houbolt J.J.H.C., 1968, Recent sediments of the Southern Bight of the North Sea, Geologie Mijnb, 47, 245

10.1130/0016-7606(1975)86<1511:VPOMBI>2.0.CO;2

Jackson R.G., 1976, Depositional model of point bars in the lower Wabash River, J. sedim. Petrol, 46, 574

10.1111/j.1365-3091.1976.tb00097.x

Jopling A.V., 1968, Morphology and origin of ripple‐drift cross‐lamination, with examples from the Pleistocene of Massachusetts, J. sedim. Petrol, 38, 965

10.1086/627235

Karcz I., 1973, Fluvial Geomorphology, 149

Kolb C.R., 1958, Geology of the Mississippi River deltaic plain, southeastern Louisiana, 3

10.1306/74D70A1A-2B21-11D7-8648000102C1865D

10.1038/253338a0

10.2307/209342

Leopold L.B., 1964, Fluvial Processes in Geomorphology

Ljunggren P., 1968, Some aspects on fluvial sediments and fluvial morphology. II. A study of some heavy mineral deposits in the valley of the river Lule Alv, 121

Lobeck A.K., 1939, Geomorphology

10.1130/GSAB-48-813

10.1111/j.1365-3091.1970.tb00184.x

10.2307/209717

10.1086/628208

Mollard J.D., 1973, Fluvial Processes and Sedimentation, 341

Nanson G.C.(1977)Channel migration floodplain formation and forest succession on a meandering‐river floodplain northeast British Columbia Canada.Unpublished Ph. D. Thesis Simon Fraser University British Columbia .

10.1086/628477

10.2307/3038059

Nilsson G., 1972, The Ore River and its Meanders, Uppsala Univ., Dept. phys. Geogr. Urgi Rep., 19

10.1111/j.0033-0124.1967.00001.x

10.1111/j.1467-8306.1963.tb00433.x

10.1007/3-540-31060-6_131

10.1017/S002531540000610X

10.1144/gsjgs.119.1.0175

Sundborg A., 1956, The River Klaralven, a study of fluvial processes, Geogr. Annlr, 38, 127

10.2110/pec.65.08.0116

Visher G.S., 1969, Grain size distributions and depositional processes, J. sedim. Petrol, 39, 1074

Wolman M.G., 1957, River flood plains: some observations on their formation, Prof. Pap. U.S. geol. Surv, 282

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Sedimentology

Tập 27 Số 1

3-29

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