Impacts of transect location and variations in along-beach morphology on measuring volume change

Ethan J Theuerkauf, Antonio B. Rodriguez

Research output: Contribution to journalArticlepeer-review

Abstract

Real Time KinematicGPS profile surveys are currently the most common method used by engineers and researchers for monitoring beach erosion. This study assesses the accuracy of volumetric-change measurements based on profile surveys at various beach morphologies along Onslow Beach, North Carolina. High-resolution digital elevation models (DEMs) were created from topographic data collected using a three-dimensional terrestrial laser scanner at six ∼150-m-long focus sites at annual, seasonal, and storm time intervals. Profiles were extracted from the DEMs every 0.5 m along the beach, a distance equal to the grid size, and each profile was independently used to measure volumetric change at each site. Along-beach variability in the measurements of volumetric change was analyzed to test the assumption that one transect can be used to determine volumetric change for a ∼150-m stretch of beach. Results show that the accuracy of profile-based volumetric change decreases as along-beach morphologic variability increases. At sites with beach cusps, beach nourishment, and pockets of anomalous erosion and/or accretion, less than 5 of the ∼300 transects accurately measure volumetric change to within ±10 of the true volumetric change. At the site with the lowest along-beach morphologic variability, that number only increased to 35 of the ∼300 transects. Three-dimensional surveys or closely spaced beach profiles should be employed at morphologically variable, and/or recently nourished or engineered, beaches to accurately quantify erosion and accretion over short timescales.

Original languageEnglish (US)
Pages (from-to)707-718
Number of pages12
JournalJournal of Coastal Research
Volume28
Issue number3
DOIs
StatePublished - May 1 2012

Keywords

  • Beach profiles
  • Real Time Kinematic (RTK)-GPS
  • barrier island
  • beach erosion
  • beach nourishment
  • beach volumetric change
  • coastal management
  • light detection and ranging (LIDAR)
  • terrestrial laser scanning

ASJC Scopus subject areas

  • Ecology
  • Water Science and Technology
  • Earth-Surface Processes

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