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Jang D., and Hwang, J. H., 2013. Classification method of estuary considering the climate change in South. Sea level rise attributed to climate change is expected to affect the estuaries of South Korea significantly. The seawater intrudes into the beds of river channels and into aquifers near the coastal zone, and such processes are expected to be magnified in the climate change regime. Further, flooding and erosion are expected to be intensified at the shorelines of rivers and in coastal zones. Such adverse effects are expected to occur, which will depend on the individual characteristics of different estuaries. Some of these characteristics include the volume of a tidal prism, the length of shoreline peripheral, and the bathymetries in the estuaries. Our present work modified the existing estuary classification systems to be more responsive to climate change; in particular, we have included the wave change impact. Many studies have proposed estuarine classifications recognizing the various features of each estuary. There are several ways to classify estuaries. First, estuaries can be classified with the Estuarine Circulation Classification (ECC) system. Second, Geomorphological Classification (GC) categorizes estuaries with the dominances among physical components. Third, Estuary Environment Classification (EEC) classifies with indices representing the physical processes and estuary shapes. However, these existing methods did not involve qualitative categorizations and also excluded the wave factor. They also did not include a category for the artificial estuaries, which are prevalent in Korea. Therefore, efficiently constructing a comprehensive response plan for the climate change based on these existing classification systems was not possible. Thus, a new quantitative method including the wave index and considering the artificial estuary is proposed here that can be utilized in a response to climate change. [ABSTRACT FROM AUTHOR]

Macrotidal beaches are scattered in the west coast of Korea mostly in small embayments of the ria-type coastline and islands. In contrast to well-known tidal flats, these beaches have been little studied from the hydromorphologic viewpoint. Byunsan Beach was chosen to investigate beach processes affected by winter monsoon, which creates strong waves and wind-generated currents. The multiyear (2005-2008) profiling of the beach, together with the intensive sampling of surface sediments, provided the details of morphologic characteristics of the beach. Deep water winter wave characteristics were based on the measurements of an offshore buoy. A benthic tripod was deployed on the beach to observe waves, currents, and suspended sediments during a winter storm. The estimated morphodynamic parameters suggest that Byunsan Beach be classified as an ultradissipative state during winter. The tendency of grain size toward systematically fining seaward could be explained by the lateral displacements across the beach of swash and surf zones owing to a high tidal range. In addition, the tripod observations show that a storm readily generated offshore return flows capable of considerable beach erosion. The storm waves also significantly contributed to the erosion. This may reflect that the macrotidal, open beaches in the west coast of Korea are seasonally susceptible to pronounced erosion by winter monsoon. The results of this study may be useful for evaluating man-made environmental impacts caused largely by seawalls and dykes on the natural beach state intrinsic to the west coast of Korea. [ABSTRACT FROM AUTHOR]

Abstract: The Sukmo Channel is one of the distributary channels of the tide-dominated Han River delta, and is flanked by a narrow and steep channel bank. In these areas the bank consists of tripartite subdivisions with a gently sloped upper intertidal salt marsh, steep middle intertidal zone, and gently sloped lower intertidal sand flat. A 7-m-thick succession of inclined heterolithic stratification (IHS) is developed in the middle intertidal portion, where it consists of thinly interlaminated sands and muds with a dip angle up to 10°. Smooth channel-bank surfaces are interrupted by intermittent occurrences of scarps and rill channels. In the upper to middle intertidal zone, bank-parallel scarps are up to 0.5m high and are generated by wind-induced waves during high tides. Bank-normal rills channels are 1 to 3m wide and up to 1.5m deep and mainly exist in the upper to middle intertidal zone. Rill channels develop during periods of heavy rainfall and low tides. Repeated measurements of channel-bank profiles revealed that bank morphology varies notably in the middle to lower intertidal flat, and remains stationary in the upper intertidal flat. Temporal variation of bank morphology appears to be seasonal. The upper to middle intertidal portion of the bank maintains a smooth convex-up profile during winter. The bank surface is moderately eroded up by wind-induced waves in the spring when local winds are strongest. Notable bank erosion occurs during summer when ephemeral rill channels are formed by episodic heavy rainfall events. From fall to winter, the rugged bank surface is filled with sediments deposited through sustained sedimentation. Gradually the bank surface rebuilds a smooth, convex-upward bank morphology. The continuity of IHS beds in the upper and middle intertidal zone is generally better in the dip-direction rather than the strike-direction. Rainfall-triggered rill development is mainly responsible for the strike-direction discontinuity of the IHS. Wind-induced waves coupled with tension cracks on the oversteepened bank surface produce the dip-direction discontinuities in the IHS beds. Present study highlights the complexity of tide-dominated IHS architecture that is formed in a monsoon-driven climate setting. The presence of rainfall-induced rill channels associated with tidal rhythmites can be used as an unequivocal evidence of intertidal IHS. [Copyright &y& Elsevier]

Typhoons can often cause inundation in lower coastal cities by inducing strong surges and waves. Being affected by typhoon annually, the coastal cities in South Korea are very vulnerable to typhoons. In 2016, a typhoon 'CHABA', with a maximum 10 min sustained wind speed of about 50 m/s and a minimum central pressure of 905 hPa, hit South Korea, suffering tremendous damage. In particular, 'CHABA'-induced coastal inundation resulted in serious damage to the coastal area of Busan where a lot of high-rise buildings and residential areas are concentrated, and was caused by the combined effect of tide, surge, and wave. The typhoon-induced surge raised sea levels during high tide, and the strong wave with a long period of more than 10 s eventually led to the coastal inundation at the same time. The present research focuses a numerical downscaling considering the effects of tide, surge and wave for coastal inundation induced by Typhoon 'CHABA'. This downscaling approach applied several numerical models, which are the Weather Research and Forecasting model (WRF) for typhoon simulation, the Finite Volume Community Ocean Model (FVCOM) for tide and surge simulation, and the Simulating WAve Nearshore (SWAN) for wave simulation. In a domain covering the Korean Peninsula, typhoon-induced surges and waves were simulated applying the results simulated by WRF as meteorological conditions. In the downscaled domain ranged near the coastal area of Busan, the coastal inundation was simulated blending a storm tide height and an irregular wave height obtained from the domain, in which each height has 1 s interval. The irregular wave height was calculated using the significant wave height and peak period. Through this downscaling study, the impact of storm tide and wave on coastal inundation was estimated. [ABSTRACT FROM AUTHOR]