• Title/Summary/Keyword: Coastal Zone

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The Effects of Female Shell Size on Reproductive Potential of the Egg Capsule in Rapa Whelk Rapana venosa in Three Regions of Different Salinities

  • Chung, Ee-Yung;Park, Kwan Ha;Lee, Chang-Hoon;Park, Young Jae
    • Development and Reproduction
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    • v.17 no.1
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    • pp.25-35
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    • 2013
  • We investigated the effects of shell height on reproductive potential of the female Rapana venosa in three regions of different salinities (the coastal zone of the Gwangyang Bay (S-1); the upper reaches (S-3); lower reaches (S-2) of the Seomjin River). The number of egg capsules, egg capsule height, and fecundity associated with reproductive potential of larger female rapa whelks were higher than those of smaller individuals in all three regions. Correlation analyses showed that there is a significant positive correlation between egg capsule and female shell height. Mean of shell heights, egg capsule heights, the number of egg capsules in an egg mass, and fecundity in an egg capsule produced from female individuals inhabiting S-1 region were markedly higher than those inhabiting S-2 and S-3 regions. In particular, the fecundity of the rapa whelk increased with the salinity and shell height. Although large rapa whelks produced a large number of egg capsules at S-1 region, those at S-3 habitat laid less egg capsules with smaller size. If these rapa whelks were put into S-2 region, the number of egg capsules produced by a female at S-2 region was slightly larger than those produced by a female at S-3 region. This provides a clear evidence that the number of the egg capsules can be controlled by the salinity. In the coastal zone of the Gwangyang Bay and the upper reaches of Seomjin River, the fecundity of this species was estimated to be approximately 182,000-1,302,000 eggs/ind./yr.

Analysis of Wave Transformation and Velocity Fields Including Wave Breaking due to the Permeable Submerged Breakwaters (수중투과성구조물에 의한 쇄파를 수반한 파랑변형 및 유속장 해석)

  • 김도삼;이광호;김정수
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.14 no.2
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    • pp.171-181
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    • 2002
  • Among various numerical methods of wave transformations including wave breaking by structure, models using VOF(Volume Of Fluid) method to trace free surface are getting into the spotlight recently. In order to analyze wave transformations and velocity of the wave fields due to the permeable submerged breakwater(PSB), This study applied VOF method to the two-dimensional wave channel installed line-source to generate waves and added dissipation zone to offer a non-reflective boundary. Hydraulic experiments was performed to obtain the application of two-dimensional numerical wave channel. The results of numerical experiments using the two-dimensional wave channel agree well with the experimental data. It was shown that vortices are formed behind the PSB, and in case of the 2-rowed PSB they also are occurred in between PSBs, strongly non-linear waves are developed on the crown of the PSB, and the direction of velocities in porous media is determined by the shape of free surface.

A Study on the Setting Criteria and Management Area for the National Ecological Network (광역생태축 구축을 위한 기준 및 관리지역 설정 연구)

  • Jeon, Seong-Woo;Chun, Joung-Yoon;Seong, Hyeon-Chan;Song, Won-Kyong;Park, Ji-Hee
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.13 no.5
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    • pp.154-171
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    • 2010
  • This study was performed to show criteria of a National Ecological Network (NEN) for South Korea and it was a part of a study of ecological network for broad areas on national land showed by Ministry of Environment of Korea. After 1970s, many european countries presented methods and criteria not on individual protected area but on networking among many habitats. The PEEN (Pan European Ecological Network) and NATURA 2000 are results of those. In South Korea, concepts and mapping metheods of ecological network was studied but those were not applied to the whole national land because the equality and local specialities were not reflected. So, in this study, we presented the criteria composed of forest, river, wildlife and coastal evaluation items in conservation ecology and showed the mapping method which can applied to the national land. After the evaluation on land area which composed of forest, river and wildlife axis. Core areas were $30,616km^2$, buffer zone were $21,870km^2$ and each accounted for 31% and 22% of the national land. Except for Taebaeck-Gangwon region, whole region's core areas were accounted for 20~30% of it and buffer zone were accounted for 20~25% of it, so these can be applied to the national land with equality and local specialities. Forest axis and river axis were clearly linear and connected, but the wildlife axis was dispersed in point form. Therefore, to apply the NEN, a detailed habitat map is important and the interconnected implementation of forest, river, wildlife, and coastal axis is required.

Analysis on the fishing conditions of tuna purse seiner belonging to the Korea-Ghana joint venture in the Atlantic Ocean (대서양 한-가나 합작법인 소속 다랑어 선망어선의 조업실태 분석)

  • KWON, Ki-Jun;LEE, Chun-Woo;KIM, Hyung-seok;RYU, Kyung-Jin;LEE, Yoo-Won
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.57 no.3
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    • pp.194-204
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    • 2021
  • The research was analyzed the catch data of the five years (2016-2020) for six joint venture company tuna purse seiners in the Atlantic Ocean, with the aim of suggesting improvement measures for responsible and sustainable fishing according to changes of recommendation by International Commission for the Conservation of Atlantic Tuna (ICCAT) on the tropical tunas. In the last five years, the average catch of six tuna purse seiner gradually increased to 7,745 tons, 8,364 tons and 9,053 tons from 2016 to 2018, but decreased to 7,761 tons in 2019 and 6,214 tons in 2020. The reason for the decrease in fishing volume in 2019 and 2020 was the fluctuation of the formation of the cold water zone (22-23℃), and the total ICCAT convention area of FAD closure in January and February due to the expansion of the FAD closure area and poor free school catching during two months period, respectively. The analysis on fishing area showed that the percentage of fishing in the high sea was about 85% although the FAD closure area included the EEZ zone in coastal countries; the rise of the fishing license in coastal countries is also believed to be a factor. In order to overcome such situations and improve catching volume, it will be possible if excellent manpower is secured, school fishing is expanded, and the production of high value-added catch (purse seine special: PS).

Hydrodynamic Response Analysis of Hybrid Floating Structure according to Length of Damping Plate (수평감쇠판 길이에 따른 하이브리드 부유식 구조물의 거동 특성 분석)

  • Min Su, Park;Youn Ju, Jeong;Young Taek, Kim
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.34 no.6
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    • pp.275-289
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    • 2022
  • New businesses such as marine leisure and floating construction have recently flourished on the coast. As a result, consideration is given to a floating structure appropriate for marine environments. In this study, we applied a damping plate to increase the stability of a hybrid floating structure that was expanded by vertical and horizontal stacking of mobile unit modules. In the numerical analysis using ANSYS AQWA, the behavioral characteristics of the floating structure were analyzed according to the length change of the damping plate. However, the wave forces acting on a floating structure are excessively calculated by the resonance of fluid surrounded by the structure in the numerical analysis using potential flow. Therefore, we used the damping zone option of the ANSYS AQWA in the frequency domain analysis.

A Study on Controlling Efflux Sediment Diffusion by Jetty Construction at Small Estuary (소규모 하구에서 토사유출 확산제어에 관한 연구)

  • Park, Sang Kil;Park, Hyun Su;Yoon, Jong Su;Lee, Si Ho
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.5B
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    • pp.483-491
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    • 2009
  • In this study, a jetty construction is taken into account for the reduction of sediment diffusive concentration incoming from the upstream river due to the urbanization and industrial development and to minimize the effects on the coastal ecosystems. The field observation and numerical calculation are conducted to analyze the diffusion zone of sediment concentration in the small estuary and coastal area. The specification of the installed jetty which is able to control the sediment concentration was decided based on the prediction of the dispersion area changes in space and time. The selected size and layout for the jetty design were examined for the dispersion zone by numerical calculation and field observation. As a result, the jetties constructed in the estuary retarded the dispersion rate of sediment concentration, so that the effect area of sediment dispersion was obviously decreased. In addition, the measured field data indicated that the sediment deposition in the inside of dikes could be controlled and the right side area of jetties could be preserved without influx sediment diffusion.

A Study on the Evaluation of Smear Zone by In-situ Tests (현장시험에 의한 Smear Zone의 평가)

  • 이장덕;구자갑
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.207-216
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    • 2003
  • To evaluate the smear zone caused by the drain installation, 10 piezometers were installed in the typical soft ground in the western coastal area of Korea. The dynamic pore water pressure developed during the drain installation was monitored using piezometers installed at a distance of 10cm, 20cm, 30cm, 40cm and 50cm from the location of the drain. The decay of pore pressure with time after pushing piezometers to depths of 5 meters and 7 meters during the drain installation was monitored to assess flow and consolidation characteristics of the soil after disturbance of the soil due to the drain installation. The drain installation results in shear strain and displacement of the soil and it decreases the permeability of the soil. Hence, the comparison between dissipation of the pore water pressure process in 10 pieszometers before as well as after installation of the drain indicated the diameter of disturbance zone and smear zone, which is related to the cross-sectional dimension of the mandrel. In addition, Cone-pressuremeter(CPM) tests were performed to obtain rigidity index of the soil for an interpretation of the dissipation processes. It has been evaluated by in-situ tests that the smear zone is from 3.0 to 3.6 times of the cross-sectional dimension of the mandrel. The hydraulic conductivity expressed in terms of the coefficient of consolidation after the drain installation was calculated from 3 to 8 times decrease evaluated by Teh & Houlsby equation and CPM test results.

A Waste Load Allocation Study for Water Quality Management of the Incheon Coastal Environment (인천해안의 수질관리를 위한 오염부하량 할당에 관한 연구)

  • Kim, So-Yeon;Choi, Jung-Hyun;Na, Eun-Hye;Park, Seok-Soon
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.1
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    • pp.43-51
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    • 2005
  • This paper presents a waste load allocation study for the Incheon coastal environment, where a computer model, called AQUASEA, was applied. A finite element mesh was constructed and refined to cover the complicated geometry of Incheon coastal sea. The tidal height at 13 places of Incheon coastal boundary and flow of the Han River were given as an input condition to the tidal simulation. All pollution sources that discharge into Incheon coast were given as input data to the water quality simulation. The modeled parameters include tidal flow and COD(Chemical Oxygen Demand). The model was calibrated and verified with the field measurements. The model results showed reasonable agreements with field measurements in both tidal flow and water quality. Systems analysis showed that the pollution load from the Han River caused recognizable impacts on the water quality of Incheon coast from Yeomhwa waterway to northern area of Younghungdo. The loads from Incheon City affected water quality from the area below Youngjongdo to the area above Jawalldo. The discharge from the Sihwa Lake caused discernible impacts on the coastal zone from the dike outlet to the Incheon harbor, and pollution loads from Kyungkido affected the sea near the Oido. An effective water quality management plan was developed from the waste load allocation analysis of the validated model, that the maximum waste loads can be discharged without violating the water quality standard given in the Incheon coastal environment.

Coastal Zone Management in the United States of America (미국의 해안관리 -New Jerseyization의 반성과 연방정부 연안역관리 프로그램의 확산-)

  • Yu, Keun-Bae
    • Journal of the Korean Geographical Society
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    • v.44 no.4
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    • pp.481-496
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    • 2009
  • Every coastal area exhibits its own unique landscape owing to the combination of the natural and cultural processes. Coastal barrier islands well show the cultural aspects of American coastal landscapes. Some 47% of barrier island area was occupied by urban and built-up area in New Jersey, while some 5% in Georgia. Tourism-related development is back to in the mid 19C. in N.J. due to the closeness to heavily populated areas such as New York and Philadelphia. Developments without proper understanding the nature of coastal processes caused New Jerseyization, the destruction of the beauty or naturalness. It was mainly due to the lack of growth-control policies and the foresight for the future coast in the processes of legislation. North Carolina's islands experienced an increase of 269% in urbanized acreage between 1956 and 1976. However, N.C. exercised her wisdom to recover the naturalness of the coastal environs: all engineering structures are banned on the beaches. Nine out of 13 barrier islands in Georgia exist in the wilderness condition owing to her unique history. The remaining islands still experienced the least development. After the Civil War most of Georgian islands were owned by rich families and maintained as wilderness. In the 1970s most of the uninhabited islands were sold or donated to research institutes or governmental agencies.

The Exploitation of World Fishery Resources for 10 Years under the New Regime in the Sea (신해양질서 10년후 세계어업자원 이용동향)

  • 이장욱;허영희
    • The Journal of Fisheries Business Administration
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    • v.23 no.1
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    • pp.43-87
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    • 1992
  • In this paper, state of exploitation of world fishery resources after 10 years under the new regime in the sea, called the era of exclusive economic zone (EEZ) expending up to a 200 nautical miles from coastal line, was reviewed to determine effect from establishing EEZ in the world fishery production and its export/import volume based on the fishery statistics annually published by the Food and Agriculture Organization (FAO) of United Nation. The world total production from marine living resources had a trend showing a waned increase during 1970's when most of coastal states were translated into the reality of EEZ. From mid-1980's onwards, it increased rapidly, reaching about 85 million tons . Such increase in production was basically from the Pacific Ocean, accounting for more than 60% of the world total production. Fishing areas where showed increase in the production after the new regime in the sea were the southwestern Atlantic (FAO area 41) , the eastern Indian (FAO area 57) and the whole fishing areas in the Pacific except the eastern central Pacific (FAO area 77). Increase in the production from distant-water fishing countries came from the regions of the southwest Atlantic (FAO area 41) and the southwest Pacific (FAO area 81) . The production from coastal states was up from the regions of the eastern Indian (FAO area 57) , the northwest and northeast Pacific (FAO areas 61 and 67) and the southeast Pacific (FAO area 87) . It was likely that the exploitation of the fishable stocks was well monitored in the areas of the northwest Atlantic (FAO area 21) , the eastern central Atlantic (FAO area 34) and the northeast Pacific (FAO area 67) through appropriate management measures such as annual harvest level, establishment of total allowable catch etc. The marine fisheries resources that have made contribution to the world production, despite expansion of 200 EEZ by coastal states, were sardinellas, Atlantic cod, blue whiting and squids in the Atlantic Ocean : tunas which mainly include skipjack, yellowfin and bigeye tuna, croakers and pony fishes in the Indian Ocean : and sardine, Chilean pilchard, Alaska pollock, tunas (skipjack and yellowfin tuna) , blue grenadier and blue whiting including anchoveta in the Pacific Ocean. It was identified that both fishery production and its export since introduction of the new regime in the sea were dominated by such coastal states as USA, Canada, Indonesia, Thailand, Mexico, South Africa and Newzealand. But difficulties have been experienced in the European countries including Norway, Spain, Japan and Rep. of Korea. Therefore, majority of coastal states are unlikely to have yet undertaken proper utilization as well as rational management of marine living resources in their jurisdiction during the last two decades. The main target species groups which led the world fishery production to go up were Alaska pollock, cods, tunas, sardinellas, chub and jack mackerel and anchoveta. These stocks are largely expected to continue to contribute to the production. The fisheries resources which are unexploited, underexploited and/or lightly exploited at present and which will be contributed to the world production in future are identified with cephalopods, Pacific jack mackerel and Atlantic mackerel, silver hake including anchovies. These resources mainly distribute in the Pacific regions, especially FAO statistical fishing areas 67, 77 and 87. It was likely to premature to conclude that the new regime in the sea was only in favour of coastal states in fishey production.

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