• Title/Summary/Keyword: Coastal control

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Study on the Cold Mass Occurrence in the Eastern Coast of the Korean Peninsula in Summer (하계 한국동해안 냉수대 발생의 시공간적 분포특성)

  • Suh Young-Sang;Hwang Jae-Dong
    • Journal of Environmental Science International
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    • v.14 no.10
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    • pp.945-953
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    • 2005
  • Daily time series of longshore sea surface temperature (SST) data at 3 stations, sea surface SST data at 58 stations in the eastern coast of the Korean Peninsular from 2001 to 2005 were used in order to study the temporal and spatial variations of the upwelling coastal cold water occurred in summer season. When the cold water occurred, SST has been decreased more than $-5^{\circ}C$ in a day. The cold water occurred frequently in the eastern coastal areas of Korea such as Ulgi, Kampo, Jukbyun. Daily variations of cold water temperature were quantified using remote control buoy system at Kijang in the southeastern coastal water from July to August in 2004. Hourly variations of SST occurred around $\pm3^{\circ}C$ when cold water disappeared at Kijang. There were close relationship between the strength of East Korean Warm Current, North Korean Cold Water and the scale of spatio-temporal cold water variations in summer season.

The Research of Beach Deformation after Construction of the Jetties

  • Park, Sang-Kil;Han, Chong-Soo;Roh, Tae-Young;Park, O-Young;Ahn, Ik-Seong;Lee, Ji-Hun
    • International Journal of Ocean System Engineering
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    • v.1 no.4
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    • pp.185-191
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    • 2011
  • This research was described the prevention of coastal topographical change and sediment diffusive concentration incoming from small estuary after construction jetties. This structure is constructed to decrease sediment deposition incoming from the upstream river due to the urbanization and industrial development and to minimize effects on the coastal ecosystem. The physical modeling and numerical modeling for waves were conducted to analyze the configuration of Imrang sand beach deformation without and with construction of jetty. The specification of the installed jetty, which is able to control sedimentation concentration was decided based on the prediction of the Imrang beach area changes by space and time. As a result, the jetties constructed in the estuary retarded the rate of sand sediment, so that the effect area of sand sedimentation was obviously decreased. In addition, the measured field data indicated that the sediment deposition inside of dikes could be controlled and the right side area of jetties could be preserved without sediment deposition.

Variation Characteristics of Haeundae Beach using Video Image (비디오 영상 기반의 해운대 해빈 변동특성)

  • Kang, Tae-Soon;Kim, Jong-Beom;Kim, Ga-Ya;Kim, Jong-Kyu;Hwang, Chang-Soo
    • Journal of Ocean Engineering and Technology
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    • v.31 no.1
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    • pp.60-68
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    • 2017
  • In this study, we analyzed the real time video image obtained from the video monitoring system to grasp the shoreline, beach width, and area change of Haeundae beach. The video monitoring techniques enabled continuous monitoring for a long period at a much lower cost than general survey methods. It was possible to grasp quantitative beach variation characteristics of Haeundae beach through image acquisition, rectification, and image processing of video images. According to the monitoring results, the erosion rate of Haeundae beach in spring and summer was -19.8% in 2014 and -6.7% in 2015. The erosion rate in 2016 was -6.4%, which showed that the erosion rate in spring and summer continued to decrease. In particular, the influence of the erosion at the time of typhoon CHABA was revealed to be smaller than in the past. It can be concluded that these variations were due to beach width expansion by beach nourishment and the installation of submerged breakwaters.

Characterization of a Unique New Strain Named the NFRDI N°1 Rotifer Strain, a Brackish Brachionus Rotifer Collected from a South Korea Coastal Lagoon

  • Jung, Min-Min
    • Fisheries and Aquatic Sciences
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    • v.14 no.4
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    • pp.333-337
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    • 2011
  • A new and a unique Brachionus rotifer was found in Hwajinpo coastal lagoon in Gangwon Province, South Korea. This Brachionus certainly originated from the wild rather than from aquaculture stations because Hwajinpo coastal lagoon has been under rigorous control as a military protected area and therefore could not have been contaminated by aquaculture stations. The new strain was identified as Brachionus rotundiformis based upon its morphological characteristics. The parthenogenetic female of this new rotifer strain typically shows characters similar to those of B. rotundiformis, such as the pot shape of the body, rounded dorsal plate compared with flattened ventral plate, elliptical mictic egg, four frontal spines, six pointed occipital spines, non-nodal foot, two toes, trophi typical of the Brachionus genus with five uncus plates resembling comb teeth, one wide symmetrical manubrium and ramus, and no stiffened spine as is seen in freshwater Brachionus rotifers. Moreover, its lorica was rather small in size compared with other common rotifer strains that serve as live-food organisms (Guam, Thai, and Bali strains). This new and unique Korean brackish rotifer, a B. rotundiformis strain, was therefore named the National Fisheries Research and Development Institute (NFRDI) $N^{\circ}1$ rotifer strain.

Summer Pattern of Phytoplankton Distribution at a Station in Jangmok Bay

  • Lee, Won-Je;Shin, Kyoung-Soon;Jang, Pung-Guk;Jang, Min-Chul;Park, Nam-Joo
    • Ocean Science Journal
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    • v.40 no.3
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    • pp.109-117
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    • 2005
  • Daily changes in phytoplankton abundance and species composition were monitored from July to September 2003 (n=47) to understand which factors control the abundance at a station in Jangmok Bay. During the study, the phytoplankton community was mainly composed of small cell diatoms and dinoflagellates, and the dominant genera were Chaetoceros, Nitzschia, Skeletonema and Thalassionema. Phytoplankton abundance varied significantly from $6.40{\times}10^4$ to $1.22{\times}10^7$ cells/l. The initially high level of phytoplankton abundance was dominated by diatoms, but replacement by dinoflagellates started when the NIP ratio decreased to <5.0. On the basis of the N/P and Si/N ratios, the sampling periofd could be divided into two: an inorganic silicate limitation period (ISLP, $14^{th}$ $July-12^{th}$ of August) and an inorganic nitrogen limitation period (INLP, $13^{th}$ of August - the end of the study). Phosphate might not limit the growth of phytoplankton assemblages in the bay during the study period. This study suggests that phytoplankton abundance and species composition might be affected by the concentrations of inorganic nutrients (N and Si), and provides baseline information for further studies on plankton dynamics in Jangmok Bay.

A Study on the Evaluation of Deterioration Properties of Reinforced Concrete Applied Repair Material and Method System by Long Term Exposure Experiment (장기폭로실험에 의한 철근콘크리트 보수재료공법 시스템의 열화특성 평가에 관한 연구)

  • Choi, Hyeong-Gil;Shin, Kwan-Soo;Shin, Seung-Bong;Na, Chul-Sung;Kim, Gyu-Yong;Kim, Moo-Han
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2007.04a
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    • pp.129-132
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    • 2007
  • In this study, for the establishment of the performance evaluation methods of repair material and method for reinforced concrete structure and the quality control standards of durability recovery method, the quantitative exposure data by exposure experiment under the coastal and normal atmosphere environment is accumulated and analyzed. Investigating and evaluating the result of exposure experiment during 54 months of exposure age under the coastal and normal atmosphere environment, Micro crack, swelling and spatting of surface coating material, crack of repair boundary parts and the great potential difference between repair part and non-repair part were somewhat generated. And the result shown that exposure specimen of coastal environment had lower electrode potential than exposure specimen of normal atmosphere environment.

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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.

Causes of Weakening Tree Vigor of Pinus thunbergii in Hanbando Coastal Forest in Shinangun, Jeollanamdo Province (전남 신안군 한반도해송숲의 곰솔 수세약화 원인 분석)

  • Kim, Sun-Hwa;Park, Seo-Gon
    • Korean Journal of Environment and Ecology
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    • v.35 no.4
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    • pp.398-407
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    • 2021
  • This study intended to identify causes of poor tree vigor in the Hanbando coastal forest by investigating its geographical environment, climate condition, soil physicochemical characteristics, and growth condition of Pinus thunbergii. It divided the forest into an area with poor tree vigor or dead standing trees and a control area with good tree vigor and examined them separately. The survey showed that stand density was significantly higher in the area with poor tree vigor. In contrast, the crown width in the area with good tree vigor was wider. The number of dead standing trees and the stand density showed a negative correlation. The stand density and diameter at breast height (DBH), tree height, crown height, and crown width also showed a negative correlation. The result indicated that, as the tree's stand density increases, the crowns of individual trees overlapped and the lower branches died. Then crown height and crown width decreased, and the number of leaves and photosynthesis was reduced, leading to lower tree height and weaker growth of breast diameter. As a result, tree vigor weakened, and combined with environmental pressures from the lack of moisture and nutrients in coastal soil and salty wind, P. thunbergii in coastal areas is expected to die massively. Although the causes of dead standing trees and poor tree vigor of P. thunbergii in the Hanbando coastal forest are complicated, poor management of adequate tree density in response to the growth of P. thunbergii is the primary cause. The secondary cause is external environmental pressures, including unfavorable soil conditions and salty and strong wind that obstruct the growth of P. thunbergii.

Prevalence and Density of Digenetic Trematode Metacercariae in Clams and Oysters from Western Coastal Regions of the Republic of Korea

  • Sohn, Woon-Mok;Na, Byoung-Kuk;Cho, Shin-Hyeong;Lee, Won-Ja
    • Parasites, Hosts and Diseases
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    • v.55 no.4
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    • pp.399-408
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    • 2017
  • A survey was performed to know the recent infection status of digenetic trematode metacercariae in clams and oysters from 4 sites in western coastal regions of the Republic of Korea (=Korea). Four species of clams (Mactra veneriformis, Ruditapes philippinarum, Cyclina sinensis, and Saxidomus purpuratus) were collected from Taean-gun, Chungcheongnam-do (Province), Buan-gun (County) and Gochang-gun, Jeollabuk-do, and oysters, Crassostrea gigas, from Shinan-gun, Jeollanam-do were transferred to our laboratory on ice and examined by the artificial digestion method. The metacercariae of Himasthla alincia were detected in 3 species of clams, M. veneriformis, R. philippinarum, and C. sinensis from the 3 surveyed areas. The positive rate and the mean density per clam infected were 98.9% (30.8 metacercariae) in M. veneriformis, 60.0% (5.0) in R. philippinarum, and 96.0% (28.4) in C. sinensis. The positive rate (mean density) of Acanthoparyphium tyosenense metacercariae in M. veneriformis was 50.0% (2.1) from Taean-gun and 70.0% (2.8) from Gochang-gun. The metacercariae of Parvatrema spp. were detected in M. veneriformis and R. philippinarum from Taean-gun and Gochang-gun; the positive rate (mean density) was 63.3% (4,123) and 50.0% (19) in M. veneriformis, and 6.7% (126) and 100% (238) in R. philippinarum from the 2 regions, respectively. The metacercariae of Gymnophalloides seoi were detected in all 30 oysters from Shinan-gun, and their average density per oyster was 646. From the above results, it has been confirmed that more than 3 species of metacercariae are prevalent in clams from the western coastal regions, and G. seoi metacercariae are still prevalent in oysters from Shinan-gun, Jeollanam-do, Korea.

Scale Effects of Stability Parameters in the Hydraulic Model Tests of Rubble Mound Coastal Structures (사석구조물(捨石構造物)의 안정성(安定性)에 관한 수리모형(水理模型)의 축척효과(縮尺効果))

  • Ryu, Cheong Ro
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.7 no.3
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    • pp.111-119
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    • 1987
  • Scale effects of stability, run-up, run-down and reflection of layered coastal structures are investigated through the experiments with 7 kinds of hydraulic scale models. The occurrence mechanism and the control method of scale effects are also discussed. As a result, it is found that the similarity of permeability of inner layers plays an important role in the occurrence of scale effects, which has been neglected in the most of conventional model tests. To assure the best scale effects for permeable coastal structures, control of Reynolds numbers of the porous media flow in each layer is recommended. It is also found that Reynolds numbers in revetment, filter, and core layer must be greater than $2{\times}10^4$, $3{\times}10^3$, and $1{\times}10^3$, respectively.

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