Analysing decadal-scale crescentic bar dynamics using satellite imagery

Analysing decadal-scale crescentic bar dynamics using satellite imagery: A case study at Anmok beach, South Korea

Athanasiou, Panagiotis (Deltares)
de Boer, W.P. (TU Delft Rivers, Ports, Waterways and Dredging Engineering; Deltares)
Yoo, Jeseon (Korean Institute of Ocean Science and Technology (KIOST))
Ranasinghe, Roshanka (Deltares; IHE Delft Institute for Water Education; University of Twente)
Reniers, A.J.H.M. (TU Delft Environmental Fluid Mechanics)

2018-11-01

Understanding long-term sandbar dynamics can be crucial for informed coastal zone management, but is often hampered by data availability. To increase the number of sandbar observations available from bathymetric surveys, this study proposes and evaluates a method to manually extract the sandbar location using freely available satellite imagery for the case study of Anmok beach in South Korea. Validation of the satellite extracted sandbar locations against 9 in-situ measurements shows good agreement with errors well within the pixel resolution of the satellite imagery (i.e. 30 m for Landsat missions). The applicability of the method is constrained to locations where (1) the cross-shore crescentic length scales are larger than the image resolution, (2) frequent wave breaking and clouds are absent and (3) the water clarity is sufficient to enable the manual extraction of the sandbar crest line. Using the additional sandbar observations from the satellite imagery significantly increases the temporal extent and resolution of the dataset for Anmok beach. This allows the study of sandbar characteristics, dynamics and impacts of human interventions to an extent that would not have been possible without the satellite imagery. Within the study period 1990–2017 it is found that the sandbar maintains a persistent crescentic pattern that is only altered during prolonged and very intense storm conditions. The cumulative alongshore migration of the sandbars is investigated and found to be in the order of hundreds of meters over the 27 years study period. Comparing the sandbar characteristics prior and after the construction of Gangneung port shows that both the amplitudes and wavelengths of the sandbar crescents near the port have decreased after its construction.

Anmok beach
Crescentic sandbars
Human interventions
Sandbar dynamics
Satellite imagery

http://resolver.tudelft.nl/uuid:9521b0ac-bb4d-4bfd-a7df-84acae5c95b8

https://doi.org/10.1016/j.margeo.2018.07.013

2019-02-04

0025-3227

Marine Geology, 405, 1-11

Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2018 Panagiotis Athanasiou, W.P. de Boer, Jeseon Yoo, Roshanka Ranasinghe, A.J.H.M. Reniers