Assessing the Performance of a Low-Cost Method for Video-Monitoring the Water Surface and Bed Level in the Swash Zone of Natural Beaches

Raimundo Ibaceta, Rafael Almar, Patricio Catalán, Chris Blenkinsopp, Luis Pedro Almeida, Rodrigo Cienfuegos

Research output: Contribution to journalArticle

5 Citations (Scopus)
19 Downloads (Pure)

Abstract

A method to continuously measure bed and water levels along a cross-shore transect of vertical poles is evaluated. This remote sensing based method uses video imagery of swash flows propagating past an array of vertical poles buried on the beach face. Using datasets collected at two beaches in Chile, the method is compared against measurements obtained with conventional co-localized instruments: LiDAR and ultrasonic distance meters. The present video swash pole technique shows good skill in retrieving swash zone bed level and water levels, while providing the possibility to measure morphological variations at time scales varying from wave groups (tens of seconds) to hours. Discrepancies between video and ultrasonic distance meters are found when short time scales are used, for both depositional and erosion events, but longer duration trends are captured well. Water surface elevations at the wave-by-wave scale proved to be accurate for the backwash phase (root-mean-sqaure-error, RMSE down to 0.028 m, R 2 up to 0.89), when compared against LiDAR. However, discrepancies have been found during the uprush phase (RMSE up to 0.062 m, R 2 down to 0.71), when the influence of the pole on the swash flow generates an overestimation of the water surface. Overall, owing to its simplicity of deployment, low cost and reasonable accuracy, the technique is considered suitable for swash studies.

Original languageEnglish
Article number49
Pages (from-to)1 - 20
Number of pages20
JournalRemote Sensing
Volume10
Issue number1
DOIs
Publication statusPublished - 2 Jan 2018

Keywords

  • Image processing
  • LiDAR
  • Shore face
  • Swash zone dynamics
  • Ultrasonic distance meter
  • Video swash pole

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)

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