On the ecogeomorphological feedbacks that control tidal channel network evolution in a sandy mangrove setting

B. van Maanen*, G. Coco, K. R. Bryan

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

An ecomorphodynamic model was developed to study how Avicennia marina mangroves influence channel network evolution in sandy tidal embayments. The model accounts for the effects of mangrove trees on tidal flow patterns and sediment dynamics. Mangrove growth is in turn controlled by hydrodynamic conditions. The presence of mangroves was found to enhance the initiation and branching of tidal channels, partly because the extra flow resistance in mangrove forests favours flow concentration, and thus sediment erosion in between vegetated areas. The enhanced branching of channels is also the result of a vegetation-induced increase in erosion threshold. On the other hand, this reduction in bed erodibility, together with the soil expansion driven by organic matter production, reduces the landward expansion of channels. The ongoing accretion in mangrove forests ultimately drives a reduction in tidal prism and an overall retreat of the channel network. During sea-level rise, mangroves can potentially enhance the ability of the soil surface to maintain an elevation within the upper portion of the intertidal zone, while hindering both the branching and headward erosion of the landward expanding channels. The modelling results presented here indicate the critical control exerted by ecogeomorphological interactions in driving landscape evolution.

Original languageEnglish
Article number20150115
Number of pages24
JournalProceedings of the royal society a-Mathematical physical and engineering sciences
Volume471
Issue number2180
DOIs
Publication statusPublished - 8 Aug 2015
Externally publishedYes

Keywords

  • tidal channel networks
  • mangroves
  • biophysical interactions
  • numerical modelling

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