The origin and development of the Nyl River floodplain wetland, Limpopo Province, South Africa: trunk–tributary river interactions in a dryland setting

McCarthy, Terence S; Tooth, Stephen; Jacobs, Zenobia; Rowberry, Matthew D; Thompson, Mark; Brandt, Dion; Hancox, P John; Marren, Philip M; Woodborne, Stephan; Ellery, William F N

Title: The origin and development of the Nyl River floodplain wetland, Limpopo Province, South Africa: trunk–tributary river interactions in a dryland setting
Creator: McCarthy, Terence S
Creator: Tooth, Stephen
Creator: Jacobs, Zenobia
Creator: Rowberry, Matthew D
Creator: Thompson, Mark
Creator: Brandt, Dion
Creator: Hancox, P John
Creator: Marren, Philip M
Creator: Woodborne, Stephan
Creator: Ellery, William F N
Date Issued: 2011
Date: 2011
Type: text
Type: article
Identifier: http://hdl.handle.net/10962/144321
Identifier: vital:38331
Identifier: DOI: 10.1080/03736245.2011.619324
Description: The Nyl River floodplain wetland, one of South Africa's largest floodplain wetlands and a Ramsar site of international conservation importance, is located in an area of long-term and still active valley sediment accumulation. Creation of accommodation space for sedimentation has previously been attributed to tectonic controls, but new investigations reveal that a more likely cause is progradation of coarse-grained tributary fans across the narrow river valley downstream of the main area of floodplain wetland. Obstruction of trunk river flow and sediment transfer by these tributary fans has led to backponding and upstream gradient reduction and to accumulation of valley fills up to ∼35 m thick. Chronological control for the timing and rate of sediment accumulation is limited, but we hypothesise that a semi-arid to arid climate, characterised by asynchronous trunk–tributary activity that results in marked discontinuities in downstream water and sediment transfer, is likely to have been a key control. These interpretations are supported by other studies of dryland rivers globally and the findings add to our growing understanding of the controls on the origin and development of southern African wetlands, particularly by demonstrating how the combination of a particular physiography and a dryland climate can impart some distinctive geomorphological characteristics.
Format: 19 pages
Format: pdf
Language: English
Relation: South African Geographical Journal
Relation: McCarthy, T.S., Tooth, S., Jacobs, Z., Rowberry, M.D., Thompson, M., Brandt, D., Hancox, P.J., Marren, P.M., Woodborne, S. and Ellery, W.N., 2011. The origin and development of the Nyl River floodplain wetland, Limpopo Province, South Africa: trunk–tributary river interactions in a dryland setting. South African Geographical Journal, 93(2), pp.172-190.
Relation: South African Geographical Journal volume 93 number 2 172 190 September 2011 2151-2418
Rights: Publisher
Rights: Use of this resource is governed by the terms and conditions of the Taylor and Francis Terms and Conditions statement (https://www.tandfonline.com/terms-and-conditions)

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