Derivation of Annual Reach-Scale Sediment Transfers in the River Coquet, Northumberland, UK

  1. Michael D. Blum5,
  2. Susan B. Marriott6 and
  3. Suzanne F. Leclair7
  1. Ian C. Fuller1,
  2. Andrew R. G. Large2,
  3. George L. Heritage3,
  4. David J. Milan4 and
  5. Martin E. Charlton2

Published Online: 17 MAR 2009

DOI: 10.1002/9781444304350.ch4

Fluvial Sedimentology VII

Fluvial Sedimentology VII

How to Cite

Fuller, I. C., Large, A. R. G., Heritage, G. L., Milan, D. J. and Charlton, M. E. (2005) Derivation of Annual Reach-Scale Sediment Transfers in the River Coquet, Northumberland, UK, in Fluvial Sedimentology VII (eds M. D. Blum, S. B. Marriott and S. F. Leclair), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304350.ch4

Editor Information

  1. 5

    Baton Rouge, Louisiana, USA

  2. 6

    School of Geography and Environmental Management, University of the West of England, Bristol BS16 1QY, UK

  3. 7

    Department of Earth and Environmental Sciences, Tulane University, Dimwiddie Hall, New Orleans, LA 70118, USA

Author Information

  1. 1

    School of People, Environment and Planning, Massey University, Palmerston North, New Zealand

  2. 2

    Department of Geography, University of Newcastle, Newcastle upon Tyne, NE1 7RU, UK

  3. 3

    Division of Geography, School of Environment and Life Sciences, University of Salford, Manchester, M5 4WT, UK

  4. 4

    Geography and Environmental Management Research Unit, University of Gloucestershire, Cheltenham, GL50 4AZ, UK

Publication History

  1. Published Online: 17 MAR 2009
  2. Published Print: 15 FEB 2005

Book Series:

  1. Special Publication Number 35 of the International Association of Sedimentologists

Book Series Editors:

  1. Ian Jarvis

Series Editor Information

  1. School of Earth Sciences and Geography, Centre for Earth and Environmental Science Research, Kingston University, Penrhyn Road, Kingston-upon-Thames KT1 2EE, UK

ISBN Information

Print ISBN: 9781405126519

Online ISBN: 9781444304350

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Keywords:

  • annual reach-scale sediment transfers in River Coquet, Northumberland, UK;
  • cross-profiles and planform;
  • DEM generation;
  • volumetric change for each morphological unit;
  • DEM accuracy;
  • sediment transfers;
  • digital elevation models in 1 km reach of River Coquet at Holystone - providing accurate representation of channel morphology

Summary

Measurement of three-dimensional morphological change in a river channel provides a useful means of assessing reach-scale rates and patterns of fluvial sediment erosion, transfer and deposition. The morphological sediment budgeting techniques used to generate these estimates of sediment flux may be particularly valuable in unstable gravel bed rivers, owing to the inherent difficulties associated with direct measurement of bedload transport. This paper compares two approaches used to derive a measure of annual sediment transfers within a 1 km long piedmont reach of the gravel-bed River Coquet in Northumberland, northern England, which has a locally braided channel planform and has experienced lateral instability over the past 150 yr. The first technique utilized channel planform and cross-profile surveys based on theodolite-EDM survey of (i) 21 monumented channel cross-profiles and (ii) channel and gravel bar margins. The second method used theodolite–EDM surveys to generate a series of xyz coordinates for the channel and bars within the reach, from which digital elevation models (DEMs) can be constructed. Calculating the difference between two DEM surfaces provides a measure of volumetric change between surveys. The compatibility between the two exercises, carried out during the springs of 1999 and 2000, was assessed by an error analysis comparing the surveyed cross-profiles with sections abstracted from the DEMs. This indicates a mean gross error between surveyed and DEM profiles of approximately twice the value of the D50 of the surface sediment in the reach. The accuracy of the DEMs as a representation of the terrain surface is quantified using residual analysis, which indicates that more than 96.3% of the interpolated surface is accurate to ±5 cm (equivalent to the surface sediment D50) for both the 1999 and 2000 DEM surfaces. Comparison of sediment volumes derived from the two approaches suggests that, relative to the higher resolution DEM survey, estimation of sediment transfers using monumented profiles and planform underestimates the magnitude of volumetric changes that occur within the reach. The degree of underestimation is reach and time dependent. The DEM method using a carefully designed sampling strategy based on morphological units provides a rigorous identification of spatial patterns of erosion and deposition, which cross-section-based approaches may fail to include.