• Journal of the Korean Association of Geographic Information Studies
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• v.9 no.1
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• pp.101-115
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• 2006

As coastal erosion is increasing sharply because of sudden changes in the natural environment and increases in artificial development, the problem of coastal erosion become an important issue, socially and economically. To building the data which needed to grasp the situation and find a solution, we need the monitoring system for long-term. In this study, we analyzed the coastal topography and land cover changes in the Haeundae Beach during 60 years. The Haeundae Beach is the most famous beach in the country and coastal erosion are going on. First, we analyzed the change of coastal topography by calculated the coastline and area of the beach using aerial photos during 60 years. We extracted the coastline by digitized on aerial photo and corrected the height of tide level using sounding and GPS survey data. And we computed the area of beach and analyzed the change of area during 60 years. Second, we analyzed the change of land cover using landcover map. We made the detailed landcover map by on-screen digitizing and estimated the soil loss for the area nearby Haeundae Beach. As a result, we could see that the coastline get nearer to land and the area of beach has been reduced in general. We think that interception of sand supply by the development is the artificial cause of coastal erosion. The result of this study would be useful in long-term coastal monitoring and to analyze the cause of coastal environment change. We expect that the result is available on the coastal information system.

• Journal of the Korean Geographical Society
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• v.48 no.3
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• pp.321-335
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• 2013

High resolution data for the coastal sand beach during short-term in Jinbok-ri, Uljin-gun, Gyeongsangbuk-do are obtained by terrestrial LiDAR. The micro-geomorphological changes of 8 times before and after the strong low-pressure events during June to September, 2009 and changes under the various environments of wave-energy are investigated in the study. The obvious geomorphological changes between the northern and southern sand beach in Jinbok-ri are revealed by terrestrial LiDAR as well as by grain size analysis. The strong waves by the typhoons decrease the area and volume of the beach, and especially the area is largely influenced. The erosive and depositional processes dominate the northern and southern sand beach, respectively, after high wave in September. These results suggest that lots of sand grains in the beach are largely re-transported within the beach rather than offshore.

• Journal of The Geomorphological Association of Korea
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• v.25 no.4
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• pp.117-129
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• 2018

Dongmag beach area contains diverse geological and geomorphological outcrops which can be used for geotourism purposes. They are as follows; headland with granodiorite with plenty of enclaves and sandy beach, which is fed from Manisan with well-developed sheeting joints composed of granite and granodiorite. Weathered material from the hillside feedsthe one and only sandy beach in Ganghwado Island. Weathered outcrop at the hillside behind beach exposes typical spherical weathering also. Bunori Dondae Fort which was built on top of sea cliff with granodiorite has plenty of history and cultural values commands an extraordinary view of tidal flats and coastal landforms. This geosite with high geodiversity can be used for interpreters who provide balanced views of nature conservation.

• Journal of Ocean Engineering and Technology
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• v.33 no.6
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• pp.581-589
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• 2019

In order to understand the characteristics of beach deformation, in this study, numerical simulations were conducted using a 3-D hydro-morphodynamic model (HYMO-WASS-3D) to analyze the characteristics of beach deformation due to the coastal groundwater levels. HYMO-WASS-3D directly analyzed the nonlinear interaction between the hydrodynamic and morphodynamic processes in the coastal area. The simulation results of HYMO-WASS-3D showed good agreement with the experimental results on the changes in the profile of the beach in the surf and swash zones. Then, numerical simulations were conducted to examine the characteristics of beach deformation due to the variation of the level of the coastal groundwater. As a result, the beach profiles were examined in relation to the wave breaking in the surf zone and the wave uprush and backwash in the swash zone due to the differences in the water levels. This paper also discussed the temporal and spatial distributions of the velocities, vorticities, and suspended sediments in the surf and swash zones with various levels of the coastal groundwater.

• Journal of Coastal Disaster Prevention
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• v.5 no.4
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• pp.203-210
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• 2018

It is generally known that submerged breakwaters can reduce the incoming wave energy without disturbing the beach scenery. However, a submerged breakwater is also able to cause a setup of the sea level in the protected area which is also called as water piling-up. Since the piling-up can result in longshore currents, sediment transports, and unexpected beach erosion, understanding about the piling-up process is required prior to designing the nearshore structures. In this study, the water piling-up behind a submerged breakwater is assessed in the time of storm events. For the study area, Anmok beach in Gyeonso-dong, Gangwon-do is selected. 1-year, 5-year, 10-year, and 50-year return-values were derived from Peaks-Over-Threshold(POT) method and those are applied as offshore boundary conditions for the numerical simulation. The numerical results of the piling-up were assessed with regard to the wave steepness and the height of the submerged breakwater. With increase of both significant wave height and the height of the submerged breakwater, the piling-up parameter is also increased which can lead to erosion of dry beach behind the structure.

• Journal of The Geomorphological Association of Korea
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• v.26 no.4
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• pp.47-65
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• 2019

A case study was conducted in Taean region to seek a more detailed macrotidal beach classification than existing beach classification models (Masselink and Short, 1993). Seepage and ridge & runnel were used for classification. On 20 beaches, 68 transects were surveyed 5 times using VRS-GPS. Cross-section area from the transect profiles, mean grain size from sediment analysis, significant wave height from Swan-wave modeling and beach embaymentization from aerial photograph analysis were used to identify the characteristics of the individual types. The transects were classified into 5 types in Taean region; Type 1: low tidal terrace, Type 2: low tidal terrace & ridge, Type 3: dissipative, Type 4: seasonal ridge, and Type 5: ridge & runnel. Generally, seepage was related to coarse sediment size and ridge & runnel was related to high significant wave height. Each type has different characteristics and there was a tendency between the types. The low tidal terrace type had coarse sediments, because this type is excluded from the littoral cell. In this study, the ridge and runnel type could be applied to the classification because the study area is limited only to the macrotidal environment in Taean region.

• 한국해양학회지
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• v.30 no.5
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• pp.480-492
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• 1995

Petrographic investigation has been carried out to determine the composition of the beach sediments and the affecting factors which have controlled their compositional variations from Hyupjae, Aeweol, Iho, Samyang, Hamdeok, Sehwa, Pyoseon, Jungmun, and Hwasun areas along the coast of the Cheju Island. Average mean sizes of the beach sediments are Hyupjae 2.2ø, Aeweol 0.8ø, Iho 1.4ø, Samyang 2.4ø, Hamdeok 1.6ø, Sehwa 1.5ø, Pyoseon 2.1ø, Jungmun 0.4ø, and Hwasun 0.9ø, thus, aries from 0.4 to 2.4ø. The beach sediments from Pyoseon and Hwasun areas are poorly sorted, those from Aeweol and Jungmun areas are moderately sorted and those from the rest of the areas are moderately well sorted. While-colored beach sediments in Hyupjae, Aeweol, Hamdeok, Sehwa, and Pyoseon areas are mostly composed of calcareous shells (more than 85%) such as mollusk, red algae, benthic foraminiferas, etc., whereas volcanic rock fragment is the dominant component of the black-colored beach sediments in Iho, Samyang, and Hwasun areas. Especially, the relatively white-colored beach sediment in Jungmun area, which is on e of the carbonate-dominant areas, shows a higher content of rock fragments than the other carbonate-dominant areas. The beach sediments in Pyoseon area show a high content of carbonate intercalates. Considering the contributions by organisms according to grain size, grains with the size range of 1∼2ø are mostly composed of calcareous red algae fragments, and grains with the size range of 2∼3ø consist of mollusk fragments. It is also notable that bryozoan fragments comprise about 48% of the sediment in Samyang area with the size range of 0∼1ø. The composition of the beach sediments in Cheju Island appears o be controlled by the riverine supply rate of volcanic rock fragments, the lithology of the rocks distributed ear the beaches, the direction of alongshore currents, and the direction of storms, etc.. It is suggested that the beach sediments in Iho and Samyang areas show black color because of the higher supply rate of the volcanic rock fragments from the nearby rivers, whereas those in the rest of the areas show white color due to the relatively lower content of volcanic rock fragments and higher content of carbonate components transported from shallow marine environment. In Hwasun area, the content of volcanic rock fragments is high, and they are directly from the tuffaceous rocks distributed nearby. Also, the volcanic rock fragments in Jungmun area are transported not only from the rivers nearby but also from the nearby tuffs by storm activities. The beach sediment in Pyoseon area contains a high content of carbonate intercalates, which formed in the nearby shallow marine environment through marine cementation. This indicates that active marine cementation occurs in shallow marine environment near Pyoseon area.

• Journal of Environmental Impact Assessment
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• v.20 no.3
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• pp.257-267
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• 2011

This paper examines the spatial and temporal variability in the shoreline boundary caused by artificial structures in Songdo Beach of South Korea. Quickbird Images of 2003, 2005, 2007, and 2010 extracted from Google Earth were used to identify changing trends of shoreline boundary. The most significant changes were observed in area where groins were extensively established, inducing the sand beach much narrower than before in almost 75% of the area($15070.72m^2$ in 2003 to $3877.46m^2$ in 2010). The Google Earth made it possible to identify area-wide patterns of shoreline change subject to many different type of artificial structures, which cannot be acquired by traditional field sampling. Groin heights, lengths and profiles can be modified during maintenance operations if the Google Earth monitoring indicates that the initial layout is not operating properly as a physical barrier to control sediment transport. It is anticipated that this research could be used as a valuable reference to confirm the outputs from past field researches for coastal processes to respond to storms in more visual and quantitative manner.

• Journal of Ocean Engineering and Technology
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• v.37 no.2
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• pp.68-79
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• 2023

Even though submerged breakwater reduces incident wave energy, it redistributes the coastal area's wave-induced current, sediment transport, and morphological change. This study examines the coastal hydrodynamics and the morphological response of a wave-dominated beach with submerged breakwaters installed through field observation and quasi-3D numerical modeling. The pre-and post-storm bathymetry, water level, and offshore wave under storm forcing were collected in Bongpo Beach on the East coast of Korea and used to analyze the coastal hydrodynamic response. Four vertically equidistant layers were used in the numerical simulation, and the wave-induced current was examined using quasi-3D numerical modeling. The shore normal incident wave (east-northeast) generated strong cross-shore and longshore currents toward the hinterland of the submerged breakwater. However, the oblique incident wave (east-southeast) induced the southeastward longshore current and the sedimentation in the northeast area of the beach. The results suggested that the incident wave direction is a significant factor in determining the current and sediment transport patterns in the presence of the submerged breakwaters. Moreover, the quasi-3D numerical modeling is more appropriate for estimating the wave transformation, current, and sediment transport pattern in the coastal area with the submerged breakwater.

• Journal of The Geomorphological Association of Korea
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• v.19 no.4
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• pp.59-71
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• 2012

This research was carried out to analyze long-term shoreline change on Busan Songjeong Beach using multi-temporal remote sensed data, GPS survey data and grain size analysis. As a result of multi-temporal satellite imagery analysis, the beach was stable status till early 2000s, but the erosion occurred over whole beach after the construction of shore protection road since 2000. In the result of DEM analysis, the elevation of beach reduced and the slope of berm increased after construction of shore protection road along the coast, this means the erosion environment was dominant on the beach. But the sedimentation was slightly stronger than the erosion in northern region of the beach, then the slope of berm was gentle. In the result of grain size analysis using in-situ samples, the coarsening-trend was found in southeastern region (Line E) of the beach, it is caused by strong wave energy from the outer sea. Consequently, major causes of the beach erosion in the study area were the interception of sand supply from a dune owing to shore protection road construction and scouring phenomenon by strong wave energy in southeastern region of the beach. If the topographic or artificial change will not occur in the future, the erosion in this area will continue. Therefore the prevention measures are required.