• Title/Summary/Keyword: South Korea Coastal Water

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Physical Oceanographic Characteristics in Hupo Coastal area during Summer and Autumn, 2007 (2007년 하계 및 추계 경상북도 후포연악역 물리적 해황특성)

  • Hwang, Jae-Dong;Lee, Yong-Hwa;Shim, Jeong-Min;Young, Seok-Hyun;Jin, Hyun-Gook;Kim, Young-Suk;Kwon, Kee-Young;Yoon, Sang-Chol
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.41 no.6
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    • pp.505-510
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    • 2008
  • To understand the oceanographic characteristics of Hupo coastal waters as regards the East Korean Warm Current and the North Korean Cold Current, current direction and velocity were investigated by deploying a current meter in Hupo coastal waters during the summer and fall of 2007. Wind data were obtained from the homepage of the Korea Meteorological Administration. Water temperature was measured using a temperature meter attached to the current meter and a mini log. During summer, a south wind prevailed, while during the fall the wind blew from the north. Cold surface waters occurred on a large scale in summer, while in the fall, warm bottom water occurred frequently. After mid-November, when the surface water was cooler than $15^{\circ}C$, there was no difference in water temperature between the surface and bottom layers.

An Approximate Solution for Diffraction-Induced Shoreline in a Double Headland and Comparison with Field Measurement

  • Shoaib, Muhammad;Kim, Dong Hee;Lee, Jung Lyul
    • Proceedings of the Korea Water Resources Association Conference
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    • 2016.05a
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    • pp.193-193
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    • 2016
  • In past decades beach erosion has been remarkably severe along coasts of different parts of the world, so that distinct types of coastal protective measures have been implemented; seawalls, wave-dissipating breakwaters, groins, artificial headlands or detached breakwaters have been constructed. In recent years, at Bongpeong beach, South Korea, an artificial headland was constructed to stop the beach erosion. The structure resulted in severe beach erosion of the adjoining places. In order to stop the consequences, another headland was constructed at some distance, but the construction of double headland did not prevent the erosion significantly. This paper focuses on the accurate design of the artificial double headland construction. The study presents the application of equilibrium shoreline empirical formula of parabolic type to estimate the equilibrium stages of the artificial double headland beaches and an analytic solution is presented in the present study. The research has solved the empirical formula of parabolic type to find the optimum result by considering the essential parameters that influence the erosion after the construction of double headland.

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Database of Navigational Environment Parameters (Water Depth, Sediment Type and Marine Managed Areas) to Support Ships in an Emergency

  • Kim, Tae-Ho;Yang, Chan-Su
    • Journal of Navigation and Port Research
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    • v.43 no.5
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    • pp.302-309
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    • 2019
  • This study introduces the navigational environment database(DB) compiling water depth, sediment type and marine managed areas (MMAs) in coastal waters of South Korea. The water depth and sediment data were constructed by combining their sparse points of electronic navigation chart and survey data with high spatial resolution using the inverse distance weighting and natural neighbor interpolation method included in ArcGIS. The MMAs were integrated based on all shapefiles provided by several government agencies using ArcGIS because the areas should be used in an emergency case of ship. To test the validity of the constructed DB, we conducted a test application for grounding and anchoring zones using a ship accident case. The result revealed each area of possible grounding candidates and anchorages is calculated and displayed properly, excluding obstacle places.

Reproductive Characteristics of Pacific Anchovy Engraulis japonicus from the Southern Waters of Korea (남해안에 서식하는 멸치(Engraulis japonicus)의 산란 특성)

  • Moon, Seong Yong;Baeck, Gun Wook;Lee, Mi Hee;Kim, Heeyong;Jung, Kyung Mi
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.55 no.6
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    • pp.927-937
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    • 2022
  • The reproductive characteristics of Pacific anchovy, Engraulis japonicus were investigated using samples randomly collected from the southern waters of Korea between January and December 2021. We analyzed monthly changes in maturity stages, gonadosomatic index (GSI), egg diameter, fecundity, and fork length (FL) at sexual groups maturity of 50%, 75% and 97.5%, and sex ratio (female:male). GSI value showed two peaks in May and August; however, microscopic analysis of E. japonicus gonad tissue revealed that the spawning period was from March to October. The main spawning seasons for the entire populations were from April to June and August to September. The overall sex ratio was female-biased (1 females, 0.89 male). The fecundity (F) of female anchovies ranged from 429 eggs at an FL of 8.0 cm to 13,824 eggs at an FL of 14.9 cm and the relationship between FL and F was 0.0788FL4.422. The FL at 50% group maturity was 8.26 cm for female anchovies. Based on the results, we suggest that the reproductive cycle in Pacific anchovies may be related to pulses in water temperature and the sexual cycle of the fish.

Morphological and Textural Characteristics of the Beach-dune System in South Korea, with the Possibility of a Dune Type Scheme Based on Grain-size Trend (국내 해안의 해빈-해안사구 지형 및 퇴적물 특성과 입도기반 사구유형 분석)

  • Rhew, Hosahng;Kang, Jihyun
    • Journal of The Geomorphological Association of Korea
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    • v.27 no.3
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    • pp.53-73
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    • 2020
  • Morphology and grain size distribution of coastal dunes should be well documented because they are critical to dune's buffering capacity and resilience against storm surges. The nationwide coastal dune survey produced the dataset, including beach-dune topographic profiles and grain size parameters for frontal beaches, foredunes, and inland dunes. This research investigated the dataset to describe geomorphic and textural properties of coastal dunes: foredune slopes, dune heights above approximately highest high water, mean size, and sorting, together with associated variables of coastal setting that influence coastal dunes. It also explores the possibility of a dune type scheme based on gran size trends. The results are as follows. First, the coast in which dunes are developed is the primary control on foredune morphology and sediment texture. Coastal dunes on the east coast were developed more alongshore rather than inland, with gentler slopes on the higher ground and out of coarser sand. The shore aspect contributes to this pattern because the east coast cannot benefit from prevailing northwesterly. Second, grain size trends from beaches through foredunes to inland dunes were little identified. Third, 12 dune types were identified from 69 dunes, showing the indicative capability for the status of beaches and dunes. We confirmed that the dataset could increase our understanding of the overall characteristics of coastal dune morphology and texture, though there is something to be improved, for example, establishing the refined and comprehensive field survey protocol.

Distribution of Nutrients in the Coastal Sea of Jeju Island (제주도 연안해수의 영양염류에 관한 연구)

  • Park Kil-Soon
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.15 no.4
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    • pp.255-262
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    • 1982
  • The data of 37 oceanographic stations in the coastal sea of Jeju island are compiled in terms of temperature, salinity, dissolved oxygen, silicate, nitrate and phosphate to analyge the chelnical characteristics in this region. This work was carried out during June, 1951. The concentrations of nutrients in the layer more than 50 m are generally 0.5-3 times larger than the surface layer. Each constituents in this layer are as follows: temperature ranged 11.8 to $15.4^{\circ}C$ and salinity, 33.8 to $34.8\%_{\circ}$; and also dissolved oxygen and slicate are 5.2 to 5.6ml/l and 5.6 to $9.0{\mu}g-at/l$, respectively. And nitrate and phosphate ranged 1.0 to $6.0{\mu}g-at/l$ and 0.1 to $0.5{\mu}g-at/l$, respectively. The coastal sea of Jeju island is divided into two parts in chemical view point : one is the southeastern sea of Jeju island under the influence of the Tsushima Current, md the other is the northeastern sea of Jejo island under the influence of the Yellow Sea Bottom Cold Water and the south coastal water of Korea. The north-western sea of Jeju island had relatively a cold (about $13^{\circ}C$) and low saline water (about $34\%_{\circ}$), and dissolved oxygen was higher than in the neibouring waters. It seems that in the southern area between Moseulpo and Seogwipo of Jeju island, two different Ivater masses are complicately intermixed and a tidal front is formed.

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Projecting the spatial-temporal trends of extreme climatology in South Korea based on optimal multi-model ensemble members

  • Mirza Junaid Ahmad;Kyung-sook Choi
    • Proceedings of the Korea Water Resources Association Conference
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    • 2023.05a
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    • pp.314-314
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    • 2023
  • Extreme climate events can have a large impact on human life by hampering social, environmental, and economic development. Global circulation models (GCMs) are the widely used numerical models to understand the anticipated future climate change. However, different GCMs can project different future climates due to structural differences, varying initial boundary conditions and assumptions about the physical phenomena. The multi-model ensemble (MME) approach can improve the uncertainties associated with the different GCM outcomes. In this study, a comprehensive rating metric was used to select the best-performing GCMs out of 11 CMIP5 and 13 CMIP6 GCMs, according to their skills in terms of four temporal and five spatial performance indices, in replicating the 21 extreme climate indices during the baseline (1975-2017) in South Korea. The MME data were derived by averaging the simulations from all selected GCMs and three top-ranked GCMs. The random forest (RF) algorithm was also used to derive the MME data from the three top-ranked GCMs. The RF-derived MME data of the three top-ranked GCMs showed the highest performance in simulating the baseline extreme climate which was subsequently used to project the future extreme climate indices under both the representative concentration pathway (RCP) and the socioeconomic concentration pathway scenarios (SSP). The extreme cold and warming indices had declining and increasing trends, respectively, and most extreme precipitation indices had increasing trends over the period 2031-2100. Compared to all scenarios, RCP8.5 showed drastic changes in future extreme climate indices. The coasts in the east, south and west had stronger warming than the rest of the country, while mountain areas in the north experienced more extreme cold. While extreme cold climatology gradually declined from north to south, extreme warming climatology continuously grew from coastal to inland and northern mountainous regions. The results showed that the socially, environmentally and agriculturally important regions of South Korea were at increased risk of facing the detrimental impacts of extreme climatology.

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고정화 시스템을 이용한 용균효소의 생산

  • 류병호;박종옥;진성현
    • Microbiology and Biotechnology Letters
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    • v.24 no.4
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    • pp.500-506
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    • 1996
  • Bacillus subtilis SH-1 screened from coastal sea water of South Korea was used to produce bacteriolytic enzyme. The production of bacteriolytic enzyme by immobilized cells was investigated. The optimum conditions for the continuous production of the bacteriolytic enzyme using immobilized cells were 2.4 mm diameter of 0.3% alginate beads, 20 ml/h of substrate feeding rate and 20 l/min of aeration rate. A productivity of 76.5 to 88.0 units/ml could be obtained for 25 days by continuous column reactor under the optimum conditions.

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First report of blooms of Gonyaulax poly-gramma (Gonyaulacales, Dinophyceae) in the Yeosu waters of the South Sea of Korea

  • Cho, Eun-Seob
    • Proceedings of the Korean Environmental Sciences Society Conference
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    • 2005.05a
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    • pp.241-244
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    • 2005
  • The aim of this study was to determine the first outbreaks of nontoxic Gonyaulax polygramma Stein in Yeosu waters in place of harmful Cochlodinium polykrikoides Margalef, which has occurred annually in the same coastal region since 1995. The observation of cellular arrangement and structure by electron microscopy showed that G. polygramma isolated from Yeosu waters had a few spines connecting with mem-branes and prominent longitudinal ridges on the cell surface, with a cingular dis-placement 1.5 times their cell width. Furthermore, the location of the nucleus wasposterior of large oval formation according to electron microscopy. On 6 August, 2004,the first bloom of G. pozygramma occurred, the date of own its disappearance was with a maximum cell density of 8,000 cells ml$^{-1}$ on 21 August, 2004. During the period of this study, the horizontal distribution of sea water temperature and salinity showed a strong coastal front, whereas the front of DIN (Dissolved Inoganic Nitrogen) was significantly different between the occurrence and disappearance of G. polygramma blooms. These results suggested that the process of the breakdown of stratification by wind and a low level of inorganic nitrogen play important roles in the rapid growth of G. polygrmma, which is associated with a greater robustness in growth against DIN than that of C.polykrikoides in nature.

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Characteristics of Blue Carbon Stock by Particle Size of Sediments in Unvegetated Tidal Flats : Hampyeong Bay and Dongdae Bay (비식생 갯벌에서 퇴적물 입도에 따른 블루카본 저장 특성: 함평만과 동대만)

  • Kyeong-deok Park;Dong-hwan Kang;Yoon Hwan So;Won Gi Jo;Byung-Woo Kim
    • Journal of Environmental Science International
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    • v.32 no.3
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    • pp.181-189
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    • 2023
  • In this study, sediment cores from unvegetated tidal flats in the Hampyeong Bay (west coastal wetland) and Dongdae Bay (south coastal wetland) were sampled, the blue carbon stock in the sediments was calculated, and the characteristics of the blue carbon stock were analyzed based on particle size of the sediments. The sediments in the Hampyeong Bay tidal flat had large particle size and low mud content, and the Dongdae bay tidal flat had small particle size and high mud content. The organic carbon content and blue carbon stock in the sediments were higher in the Dongdae tidal flat than in the Hampyeong Bay tidal flat. As a result of the regression function, in both the Hampyeong Bay and Dongdae Bay tidal flats, the sediments had the smaller particle size and higher mud contents the higher the organic carbon content and blue carbon stock. The sediments with smaller particle size had the larger specific surface area, so were feasible to adsorb and store more organic matters.