Effective Discharge for Overbank Sedimentation on an Embanked Floodplain along the River Waal, The Netherlands

  1. N. D. Smith3 and
  2. J. Rogers4
  1. N. E. M. Asselman

Published Online: 17 MAR 2009

DOI: 10.1002/9781444304213.ch5

Fluvial Sedimentology VI

Fluvial Sedimentology VI

How to Cite

Asselman, N. E. M. (1999) Effective Discharge for Overbank Sedimentation on an Embanked Floodplain along the River Waal, The Netherlands, in Fluvial Sedimentology VI (eds N. D. Smith and J. Rogers), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304213.ch5

Editor Information

  1. 3

    Department of Geosciences, 214 Bessey Hall, University of Nebraska, Lincoln, NE 68588-0340, USA

  2. 4

    Cape Town, South Africa

Author Information

  1. The Netherlands Centre for Geo-Ecological Research, Department of Physical Geography, Utrecht University, PO Box 80.115, 3508 TC Utrecht, The Netherlands

  1. WL/Delft Hydraulics, PO Box 177, 2600 MH Delft, The Netherlands

Publication History

  1. Published Online: 17 MAR 2009
  2. Published Print: 7 OCT 1999

ISBN Information

Print ISBN: 9780632053544

Online ISBN: 9781444304213

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Keywords:

  • modern fluvial environments;
  • effective discharge - overbank sedimentation on embanked floodplain along River Waal, The Netherlands;
  • sediment accumulation during floods of different magnitude;
  • flood magnitude;
  • effective discharge for floodplain sedimentation;
  • SEDIFLUX model developed by Middelkoop (1997) - to determine sediment-trapping efficiency curves;
  • Effective discharge - results

Summary

As little is known about the effectiveness of floods of different magnitude on floodplain sedimentation, the aim of this study was to determine the effective discharge for overbank sedimentation in The Netherlands. The study was carried out on a grass-covered, embanked, floodplain section along the River Waal, the main distributary of the River Rhine in The Netherlands. The floodplain section consists of two parts. One part is protected from low floods by a minor river dyke, whereas the other part lies adjacent to the main river channel. In the latter section, sediment accumulation was measured during a series of floods using sediment traps made of artificial grass. The measurements provide an indication of the importance of floods of different magnitude on the deposition of suspended sediment. A sedimentation model was applied to compute the long-term effective discharge for sedimentation on both floodplain sections.

The sedimentation measurements showed an increase in sediment accumulation with flood magnitude. The increase was stronger for sand than for silt- and clay-size material. Sedimentation did not increase proportionally with sediment transport rates, however, suggesting that trapping of fine-grained suspended sediment becomes less efficient at very high discharge. The model results confirm this hypothesis. On the low floodplain section, most sediment is deposited at a river discharge of about 5500 m3 s−1 or less, i.e. a discharge at which the floodplain is just inundated and which occurs, on average, about 1.3 times a year. On the floodplain section bordered by a minor river dyke, a slightly higher effective discharge for sedimentation was found (up to 7000 m3 s−1). This discharge level occurs about once every 2 yr. It is concluded, therefore, that the effective discharge for floodplain sedimentation in The Netherlands is a moderate discharge, during which the floodplain is just inundated. Such discharges occur relatively frequently.