Modes of berm and beachface recovery following storm reset: observations using a continuously scanning lidar

Matthew Phillips, Christopher Blenkinsopp, Kristen Splinter, Mitchell Harley, Ian Turner

Research output: Contribution to journalArticle

10 Citations (Scopus)
50 Downloads (Pure)

Abstract

Following the rapid and destructive impacts of storm erosion, beach recovery is a key natural process of restoration, returning eroded sediment to the subaerial beach and rebuilding coastal morphology. While the effects of storm erosion have commonly been investigated, detailed studies into post‐storm recovery are currently lacking. This study investigates wave‐driven recovery processes of the berm and beachface on a microtidal, swash‐aligned sandy beach. Following complete removal of the berm by a significant storm event, the entire 76‐day rebuilding of a swash berm is analysed at the timescale of every semi‐diurnal tidal cycle, utilising high resolution (5 Hz) swash and subaerial beach profile measurements from a continuously scanning fixed lidar. Tide‐by‐tide rates of subaerial volume change during berm recovery were most frequently observed between 1‐2 m3/m/day, including losses and gains on the order of several m3/m/day, substantially larger in magnitude than the more gradual rate of net gain (0.7 m3/m/day) observed for the entire recovery period. Patterns of berm crest formation and vertical growth were found to be primarily governed by the neap‐spring tide variations in total water levels. Tide‐by‐tide beachface and berm volume changes were used to classify four principal behavioural modes of subaerial profile variability during recovery. Using decision tree classification, modes were differentiated according to nearshore dimensionless fall velocity, swash exceedance of the berm crest and ocean water levels. The findings provide novel behavioural and parametric insight into the tide‐by‐tide rebuilding of the beachface and berm by swash throughout a complete post‐storm recovery period.
Original languageEnglish
Pages (from-to)720-736
Number of pages17
JournalJournal of Geophysical Research - Earth Surface
Volume124
Issue number3
Early online date14 Feb 2019
DOIs
Publication statusPublished - 1 Mar 2019

Keywords

  • Lidar
  • Narrabeen-Collaroy
  • accretion
  • beach recovery
  • beachface
  • berm growth

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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