Geomorphic controls on the diversity and patterns of fluvial forms along longitudinal profiles

Sana Khan*, Kirstie A. Fryirs, Timothy J. Ralph

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A mix of catchment-scale controls operate to determine geomorphic river diversity in a catchment. These are contextualised here as imposed and flux controls. Imposed controls do not adjust over geomorphic timeframes and produce the environmental setting in which a river functions. Flux controls are dynamic interactions between flow and sediment that heavily influence geomorphic river diversity. We measure and statistically analyse the network scale mix of imposed and flux controls occurring along longitudinal profiles of various shape. We use this to explain the diversity, pattern and sequence of river types at different positions in a catchment. Using the Richmond River catchment, New South Wales, Australia, as our case study we analyse the imposed controls of slope and valley bottom width and the flux controls of bed material size and gross stream power for five river types, ranging from confined continuous rivers in headwaters to laterally unconfined discontinuous rivers in lowland plains. We find that slope and gross stream power are strong, positively correlated controls on all river types, but act most strongly on rivers with continuous channels. In contrast, bed material size is a dominant control on rivers with discontinuous channels. Slope and gross stream power are also critical for determining the downstream pattern of river types along longitudinal profiles. However, the relationship between these controls is complex as not all rivers are influenced by these controls in the same way. Understanding the mix and patterns of controls operating along longitudinal profiles can be used to explain the variability and pattern of river types we see in the landscape.
Original languageEnglish
Article number105329
Pages (from-to)1-15
Number of pages15
JournalCatena
Volume203
DOIs
Publication statusPublished - Aug 2021

Keywords

  • Fluvial geomorphology
  • River adjustment
  • Boundary conditions
  • Impelling and resisting forces
  • Process domains
  • Degrees of freedom

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