Variation in suspended sediment yield across the UK - A failure of the concept and interpretation of the sediment delivery ratio

Fred Worrall*, Tim P. Burt, Nicholas J K Howden, Gregory R. Hancock

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

5 Citations (Scopus)

Abstract

The sediment delivery ratio (SDR) has been a common approach developed to understand change in sediment yield and flux through a catchment. In this study we propose that the underlying concept of the sediment delivery ratio is flawed for a number of reasons: its linear extrapolation is physically meaningless; there is no evidence of the magnitude of storage required by the SDR approach on annual to decadal timescales; and the SDR approach assumes suspended sediment transport is conservative yet it is known to undergo both loss and production in-channel. This study considers the sediment yield from 192 UK catchments from 1974 to 2010 for catchment areas between 4 and 9948km2 and shows that linear extrapolation of the SDR approach overpredicts source terms and underpredicts fluxes for large catchments. The SDR approach hides a range of behaviours of suspended sediment flux within catchments with patterns of net deposition, net increase or no change all apparent in UK catchments. The approach proved to be self-correlated which meant that it can result in spurious correlations when compared to catchment area. The change in yield with catchment area can be just as well understood as a change in sediment supply from channels rather than as a change in delivery from hillslope sources. We propose that suspended sediment flux change with catchment area be modelled as a more physically-meaningful Gompertz function (step function) rather than using the traditional SDR approach.

Original languageEnglish
Pages (from-to)1985-1996
Number of pages12
JournalJournal of Hydrology
Volume519
Issue numberPB
DOIs
Publication statusPublished - 7 Nov 2014

Keywords

  • Particulate organic matter
  • Rivers
  • SDR
  • Suspended sediment flux

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