• Journal of Ocean Engineering and Technology
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• v.23 no.1
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• pp.7-15
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• 2009

The aim of this study was to survey the effects of the beachface gradient on 3-D currents around the open inlets of submerged breakwaters. First, the numerical model was validated by a comparison with existing experimental data. This model is able to consider the flow through a porous medium with inertial, laminar, and turbulent resistance terms, i.e. simulate directly WAve?Structure?Seabed/Sandy beach interaction, and can determine the eddy viscosity with a LES turbulent model in a 3-Dimensional wave field (LES-WASS-3D). Using the numerical results of this model, the 3-D currents around the open inlets of submerged breakwaters were examined in relation to the beachface gradient. Moreover, the wave height distribution and mean flow around them are also discussed, as well as the distribution of the wave breaking points over the crest.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.452-455
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• 2009

The Nakdong Delta can be identified by two different geomorphic units. The first one is the upper delta. This is mostly composed of inter-distributary islands that are largely influenced by fluvial processes and attributed to the development of these islands along the river. The other one is the lower delta which is mostly composed of beach ridges. Barrier islands are largely effected by wave processes promoted by the development almost at a right angle to the river. Influenced by the longshore current which flows to the same direction, barrier islands located in the Nakdong river estuary are developing from east to west direction. As a result, the eastern end of the barrier islands are growing toward the north-west direction effected by tidal current which moves toward the same direction. Barrier islands include the Sinho Island, the Jinwoo Island, the Daema deung, the Janga Island, the Baghap deung, the Sae deung, and the Chulsae deung(Doyeo deung). They have orderly emerged from the sea since 1861. Since 2008, a new Deung, a sand dune growing under sea, has been developing rapidly from Chulsae deung to the Dadaepo beach. It made the sailing of small fisher boats impossible. Tidal currents transported a lot of sand and silt around the barrier islands. The landscape of Nakdong river estuary where many barrier islands are distributed will change rapidly affecting land environment.

• The Korean Journal of Quaternary Research
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• v.7 no.1
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• pp.27-39
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• 1993

The shingle beach as a typical pocket beach located in Jeongdo-ri, Wando, Cheolanam-do, Korea has been investigated in terms of textural characteristics, mainly gravel shape and roundness. In the Jeongdo-ri gravel beach, changes of beach profile after storm weather and textural parameters of gravels were observed and measured from May 1992 to March 1993. Beach profile is divided into two different Fair-weather zone and Storm-weather zone influenced by dynamic condition of wave energy. The former is affected by wave and tide under fair-weather condition, the latter seems to be formed under storm-weather condition. Each zone comprises a series of beach faces and berms formed by continuous sedimentary processes of swash, overwash and backwash. Storm-weather zone is subdivided into three groups having a pair of beach face and berm respectively. Mean sizes of berm gravel(45.5 mm -123.6 mm) are coarser than gravels of beach face (36.8 mm - 78.3 mm) in fair-weather zone. On the other hand, in storm-weather zone, gravels of berms (33.1 mm -82.5 mm) are finer than those of beachfaces (46.2 mm - 105.2 mm). The proportion of disc shaped gravels of berm (50.0% - 58.5 %) is higher than that of beachface (45.9 % - 51.3 %) in each subzone except C-group of storm-weather zone. And the proportion of the equant shaped gravel increases about up to 10% seaward. Therefore, shore-normal distribution of gravels seems to be affected by shape and size sorting effects. Shore-parallel distribution pattern of gravel shape is more distinctive than size distribution patterns. That is, disc and blade shaped particles decrease up to 20% and 13% respectively, and equants increase up to 34% to the westward. Gravels plotted on Sneed and Folk's triangular diagram are more compacted and elongated with decreasing size. Therefore primary gravels are shaped by characteristics of country rock e.g. cleavage, joint etc., and secondary are affected by sorting and size-controlled process evolution by wave action.