• Water Engineering Research
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• v.2 no.2
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• pp.75-87
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• 2001

A new moving boundary technique for leap-frog finite difference numerical mode is proposed for the resonable simulation of coastal inundation over discontinuous topography. The new scheme improves the moving boundary technique developed by Imamura(1996). The present scheme is tested using the analytical solution of Thacker(1981) for the case of free oscillation with moving boundary in a parabolic bowl. Finally, a numerical simulation is conducted for the flooding over a tidal barrier constructed on a simple concave geometry. A general feature of inundation over a discontinuous topography is well described by the numerical model.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.259-269
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• 2003

The necessary of predicting changes in tidal regime that would caused by large coastal engineering developments has been led to increased numerical modeling of tides on the continental shelf since 1970s (Flather, 1976; Choi, 1978; Greenberg, 1979). (omitted)

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.2
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• pp.113-124
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• 1984

This study represents results of analysis of sea level record at Mokpo for the years 1956~1982. The results are believed to be the first detailed analysis for the Port of Mokpo. The tidal constants are obtained from separate yearly extended harmonic analysis. The variability of these yearly analysis gives estimates of effects on astronomical tide due to Youngsan Barrier. Multiple statistics of sea level record for the years 1965~1980 and 1981~1982 are presented separately to evaluate the distribution of sea level frequency due to the construction of Barrier. Some of preliminary results are presented and indication of further studies are discussed.

• The Korean Journal of Quaternary Research
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• v.9 no.1
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• pp.33-42
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• 1995

우리나라의 서해(West Sea)는 일명 황해(Yellow Sea)라고 일컬어지는 약 40여 m의 평균 수심을 갖는 대륙붕 해저지형 분지에 의하여 지배되는 전형적 육연해이다, 그런데 이 바다는 중심부(황해의 중심부)를 기준으로 하여 중국 대륙의 산동반도에서 양가강 하구에 이르는 서부 해안을 가지며 북부에는 발해만의 해안이 있고 동부에는 서해(황해) 특유의 넓 은 조수환경(tidal environment)과 조수해안이 발달한다. 그러나 남쪽으로는 북서태평양과 연결된다. 한국 서해안이 평균 4m 이상의 조차(tidal range)를 나타내는 조간대 조수환경이 며 조간대 해저지형(intertidal morphology)이 전형적인 퇴적층(체)에 의하여 지배되는 여러 가지 특징을 나타낸다. 서해안 조수환경은 네델란드, 독일 또는 지배되는 여러 가지 특징을 나타낸다. 서해안 조수환경은 네델란드 독일 또는 미국의 경우와 같이 연구가 잘되어 세계 적으로 널리 알려진 소위 barrier island system and tidal depositional environments와는 크 게 다른 퇴적과정과 환경이다. 경기도 남양만의 조수 환경의 경우, 조간대 해저지형 요소인 조류로(tidal channel)와 조간대 정규해저(intertidal zone proper)에 관한 동력적 퇴적과정 연 구결과 조간대 특유의 lateral sedimentation 과 vertical sedimentation 2가지 퇴적과정중 후 자의 퇴적과정이 우세한 것으로 밝혀졌고 이러한 퇴적과정의 진행이 매우 안정한 지속성을 가지는 것이 특징이다, 이러한 퇴적과정의 조간대 퇴적물의 쇄설 입자는 약 20% 미만의 모 래(sand) 입자 50~70%의 실트(silt) 와 점토(clay) 입자가 20~30%에 달하는 입자조직 (grain texture)의 퇴적상을 나타낸다. 결과적으로 조간대의 동력적인 조수수괴의 수위(level of tidal water)는 평균 만조선과 평균 저조선으로 한정되며 이것은 퇴적과정과 퇴적작용의 조정(control) 요인으로 조간대 퇴적상의 발달과 분포에 큰 영향을 미친다, 예를들면 남양만 등의 대부분의 서해안 조간대 표층 퇴적상(녁\ulcorner미 sedimentary faci-es)은 만조선에서 간조 선에 가까울수록 조립화현상(coarsening trend)을 나타낸다. 이러한 퇴적상 변화는 저조선에 서 만조선으로의 조간대 지형과 주조수로의 지형.수력학적 특성이 다음과 같기 때문이다. a) a general decrease in width b) a general decrease in depth c) a general decrease in maximum and average current velocities d) a general increase in contents of suspended mud e) a general decrease in grain size of the bottom sand and an increasing abundance of muddy deposits. 우리나라 서해안 조간대 퇴적층(체)의 수직 층서(vertical stratigraphy)는 지난 3여년동안의 수십개의 vibracoring(주상시추)에 의하여 매우 흥미롭고 중요하게 밝혀지고 있는바 이것은 현세(Holocene)와 선현세(preHolocene: 11000 years BP)의 오랜시간 경과에 따른 조수환경 변화의 수직퇴적 과정과 기후 해수면 변화의 현상에 원인이 있다고 해석된다.(박용안 외, 1992-1995)결과적으로 서해안 조수퇴적체(층)의 분지주변(basim margin)진화과정이 밝혀지 고 있다.

• Journal of the Korean earth science society
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• v.22 no.2
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• pp.120-129
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• 2001

A sand shoal (1300 m long and 400 m wide) with an orientation of north-south is formed on the lower tidal flat of Gomso Bay, southwestern coast of Korea. Surface bedforms, sedimentary structures, sedimentation rate, grain size distribution and can-corer sediments have been measured and analysed along the sand shoal proper zone B and its offshore zone A and onshore zone C during the period of 14 months. These three zones can be differentiated based on sedimentological characteristics: A zone - fine sand (3${\varphi}$ mean), linguoid-type ripples, 70 mm/month in sedimentation rate and no bioturbation, B zone - medium sand (2.5${\varphi}$ mean), dunes (4${\sim}$5 m in wavelength), 30 mm/month in sedimentation rate and no bioturbation, and C zone - coarse silt (5${\varphi}$ mean), sinuous-type ripples, 10 mm/month in sedimentation rate and well-developed bioturbation. These characteristics indicate that the zone C represents a relatively low-energy regime environment whereas the zone A corresponds to a relatively high-energy environment. The zone B would play an important role for a barrier to dissipate the approaching wave energy, resulting in maintaining of low-energy conditions in the inner part of Gomso-Bay intertidal flat behind.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.79-93
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• 2008

Water quality simulations on the Saemangeum inner reservoir have been carried out using EFDC model to understand water quality variations caused by abrupt physical changes due to closing of tidal barrier. According to hydrodynamic simulation, model reproduces not only outer regional dynamics but also inner superelevation very well. Calibration and verification of water quality models accomplished using observed data taken before closing. Also sensitivity tests regarding riverine discharges and tidal flats were done. Due to enlarging of always wet zone caused by super elevation on inner tidal flats, predicted DO decreases at that region as a result of SOD. Moreover shrink of mixing zone after closing of dike causes deteriorating of water quality showing DO as 2 mg/L during summer at Mangyeong and Dongjin estuaries, however it does not spread to middle part of the reservoir. Vertical stratification occurs after closing and shows vertical differences in DO concentration at least 6 mg/L to 7 mg/L in summer season. Most part of the reservoir is getting stratified and it leads to an oxigen deficit zone near bottom.

• Ocean and Polar Research
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• v.24 no.1
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• pp.55-61
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• 2002

Eelgrass, Zostera marina L. widely spreads throughout all the coastal areas of the Korean Peninsula. However, some previously reported eelgrass populations disappeared. The disappearance was probably caused by anthropogenic disturbance such as reclamation and pollutant or exceeded nutrient release. Eelgrass beds occurred from the intertidal to the subtidal zone, mainly in lagoon, estuaries, ports, barrier reef and bays. Eelgrass beds were also found at the intertidal mud and sand flats, subtidal mud and sandbank in more exposed areas. Habitat characteristics of eelgrass beds distributed on the coasts of the Korean Peninsula varied among coast areas. Eelgrass distributed constantly throughout the southern coast of Korea, while the distribution was limited at lagoon, bay, port, or barrier reef on the eastern coast, because of steep water depth and high wave energy in that coast. On the western coast, eelgrass mainly appeared at the intertidal and subtidal zones in islands. Sediment characteristics of the Z. marina beds varied with locality, tidal current and water motion. Sediments of Z. marina beds were composed of sand, muddy sand, sandy mud and mud. Mean grain size ranged from 1.5 to 4.1 phi.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.1
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• pp.11-20
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• 2006

The Nakdong Estuary is complex water system, where sea water and fresh water meet each other. It has undergone the significant change of its environmental conditions since the construction of the Nakdong River Barrier in 1987. Prior to its construction, mixing and circulation processes in the Nakdong Estuary was dominated by tidal current. However, after the dam construction, those processes were greatly altered by the artificial control of the fresh river water discharge. In this paper, the influence of opening and closing the floodgate of Nakdong River on the outflow behavior of estuarine water from the Nakdong Estuary is analyzed in detail.

• The Korean Journal of Petroleum Geology
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• v.10 no.1_2 s.11
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• pp.10-17
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• 2004

The Doowoo-ri tidal flat in the southwestern Korean coast is a typical open-coast tidal flat which has no barriers in the offshore such as barrier island and sand bars. The difference of induced wave energy with seasons is affected directly on the distribution of surface sediment and the formation of sedimentary structures because the sedimentation by wind wave is relatively much important element in this open-coast tidal flat. This open-coast tidal flat can be classified into tidal beach, intertidal flat and lower mudflat according to the pattern of geomorphology and sediment type. The intertidal flat can be again divided into 3 types: sand flat, mixed flat and mud flat based on the primary sedimentary structure and sand/mud ratio. Doowoori tidal flat shows a seasonal change in the surface sedimentary facies based on sediment composition and primary sedimentary structure. The change is closely related to the direction and magnitude of monsoon wind and also to storm frequency. In winter and spring, when northwesterly wind is most dominant and strong and also storms are common, sand-flat facies is largely distributed on the intertidal flat, whereas mud-flat facies is most dominant during summer when weak southeasterly wind is common. In the fall season, mixed-flat facies is dominant on the flat. The Doowoori intertidal flat is covered by mud sediment which is ca. 20 cm in thickness in summer season. In winter season, surface sediment is changed from mud to sand because the summer mud is mostly eroded by strong wave action. Can-core peels in the intertidal flat show that parallel laminated mud or sand/mud and climbing ripple cross-laminated sandy silt are dominant on the upper intertidal flat $(0-1.3 {\cal}km)$ during summer season. On the other hand, on lower intertidal flat $(1.7-2.3 {\cal}km)$, dominant sedimentary facies is homogeneous mud. In winter, it is changed into parallel laminated and ripple cross-laminated sand facies.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.4
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• pp.305-313
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• 1996

CTD measurements were conducted in the Nakdong estuary on the several sections or along-plume and cross-plume directions in 1993 and 1994. Internal Froude number Fi=0.22-0.35 in ebb tides and 0.14 in flood tides suggest that Nakdong river plume may go farther seawards in the along-plume direction with little mixing with the adjacent sea water after the construction of Nakdong river barrier. From Dadae-Po to Gaduk-Do section of cross-plume direction, three cores of low salinity were found. The main plume outflows from the newly made channel by cutting Ulsuk-Do after the construction of barrier. The low salinity core found near Gaduk-Do is the plume patch advected by tidal currents. Rossby deformation radius varied with the tidal cycle so that Coriolis effect is strengthened in flood tides to deepen the isohalines westwards to the Gaduk-Do site. Internal wavelike shape was found in the section of cross-plume direction during ebb tides. Richardson number of the section suggests the possibility of forming internal wave but more precise observations are necessary.