Video Monitoring of Shoreline Positions in Hujeong Beach, Korea

Abstract

Shoreline processes observed by a video monitoring system were investigated under different wave conditions. A 30 m-high tower equipped with video cameras was constructed in Hujeong Beach, South Korea, where coastal erosion was suspected to occur. Two-year shoreline data since December 2016 showed that beach area, Ab, has decreased, but periods of rapid increase in Ab were also observed. Shoreline change was closely related to the wave propagation directions and bottom topography. Ab increased when waves approached the shore obliquely, whereas it decreased when they approached in a normal direction. The shoreline became undulated when Ab increased, while it became flatter when Ab decreased. The undulation process was influenced by nearshore bedforms because the shoreline protruded in the lee area where underwater rocks or nearshore sandbars actively developed, with a sheltering effect on waves. Specifically, the locations of shoreline accretion corresponded to the locations where the sandbar horns (location where a crescentic sandbar protrudes toward the shore) developed, confirming the out-of-phase coupling between sandbars and shoreline. When waves with higher energy approached normal to the shore, the sheltering effect of sandbars and underwater rocks became weaker and offshore sediment transport occurred uniformly along the coast, resulting in flatter shorelines.

Collapse of a Coastal Revetment Due to the Combined Effect of Anthropogenic and Natural Disturbances

“…Before the Hanul NPP was constructed in the 1980s, the beach consisted of a littoral cell including the input of sediments from a river north of the beach, which was balanced by the sediment output through the cape. However, since the breakwaters of the NPP have been built, the balance has been broken and the beach has been eroded [20]. To understand the coastal processes in this area, various experiments have been performed by the East Sea Research Institute (ESRI) of the Korea Institute of Ocean Science and Technology (KIOST) using the VMS [20] and acoustic instruments [21].…”

“…However, since the breakwaters of the NPP have been built, the balance has been broken and the beach has been eroded [20]. To understand the coastal processes in this area, various experiments have been performed by the East Sea Research Institute (ESRI) of the Korea Institute of Ocean Science and Technology (KIOST) using the VMS [20] and acoustic instruments [21]. The VMS was installed at the top of a 30 m high metal tower in the middle of Hujeong Beach (Figure 1).…”

“…vides a directional spectrum to estimate the significant wave height ( ), peak wave period ( ), and direction ( ) time series for the experimental site, is 2 Hz [20]. The wave data were estimated every 30 min continuously during the experimental periods, by constructing power density spectra on the basis of 2048 measuring points for each data burst that contained the first 17 min of data.…”

“…For wave measurement, a Nortek Acoustic Waves and Currents (AWAC) sensor has been moored at the location~1.0 km away from the coast at~19 m depth and has provided wave data since 1 July 2016. The measuring frequency of the AWAC sensor, which provides a directional spectrum to estimate the significant wave height (H s ), peak wave period (T p ), and direction (D p ) time series for the experimental site, is 2 Hz [20]. The wave data were estimated every 30 min continuously during the experimental periods, by constructing power density spectra on the basis of 2048 measuring points for each data burst that contained the first 17 min of data.…”

Applied Sciences: “Coastal Deposits: Environmental Implications, Mathematical Modeling and Technological Development”

“…Results show complex dynamics of water circulation due to different processes, including wind forcing mechanisms. Another exemplification is provided by the work of Chang Y. et al [2] in which research-based on video monitoring systems in South Korea is introduced, intending to prevent erosion by waves in a beach environment. Understanding wave incidence and maritime climate using remote sensing techniques improve the advancement in prediction models of sediment accumulation and erosion cycles.…”