• Title, Summary, Keyword: High tide

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Typhoon-Surge Characteristics and the Highest High Water Levels at the Western Coast (서해안의 태풍해일특성과 고극조위)

  • Kang, Ju Whan;Kim, Yang-Seon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.2
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    • pp.50-61
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    • 2019
  • The aspects of typhoon-induced surges were classified into three types at the Western coast, and their characteristics were examined. The typhoons OLGA (9907) and KOMPASU (1007) were the representative steep types. As they pass close to the coasts with fast translation velocity, the time of maximum surge is unrelated to tidal phase. However, typhoons PRAPIROON (0012) and BOLAVEN (1215) were the representative mild types, which pass at a long distance to the coasts with slow translation velocity, and were characterized by having maximum surge time is near low tide. Meanwhile, typhoons MUIFA (1109) and WINNIE (9713) can be classified into mild types, but they do not show the characteristics of the mild type. Thus they are classified into propagative type, which are propagated from the outside. Analyzing the annual highest high water level data, the highest water level ever had been recorded when the WINNIE (9713) had attacked. At that time, severe astronomical tide condition overlapped modest surge. Therefore, if severe astronomical tide encounter severe surge in the future, tremendous water level may be formed with very small probability. However, considering that most of the huge typhoons are mild type, time of maximum surge tends to occur at low tide. In case of estimating the extreme water level by a numerical simulation, it is necessary not only to apply various tide conditions and accompanying tide-modulated surge, but also to scrutinize typhoon parameters such as translation velocity and so on.

Treatment of Red Tide in Ocean Using Hydroxyl Radical

  • Zhitao Zhang;Mindong Bai;Xiyao Bai;Xue, Xiao-Hong
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.38-42
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    • 2004
  • A pilot-scale experiment for the treatment of red tide in the enclosure was done in sea area of Shandong Province, P. R. China on Aug. 25, 2002. With the method of strong dielectric barrier discharge in microgap, $O_2$in air and $H_2O$ in seawater are ionized and dissociated into large numbers of OHㆍradicals, and then dissolved into a part of seawater to form OHㆍsolution of high concentration. With OH' concentration of 0.68mg/L, the kill efficiencies of 29 kinds of red tide organisms such as Chaetoceros lorenzianus and so on reached 99.89%, in which the kill efficiencies of bacterium and vibrio were 100%, and that of Gonyaulax cysts and Prei. Cysts were up to 100%. At the same time, the content of chlorophyll-a was decreased into the lowest limit of test. DO saturation of seawater was greatly increased to 100% because the residual OHㆍradical was decomposed into $H_2O$ and $O_2$after 20 minutes, Therefore the treatment of red tide using OHㆍradicals is a kind of advanced oxidation technology, which realizes zero pollution, zero emission and zero residual in the process of the production of OHㆍradicals and the treatment of red tide.

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Local Movement of Shorebirds for Roosting between Ganghwa and Yeongjong Island in the West Coast of Korea

  • Kim, Hwa-Chung;Yoo, Jeong-Chil
    • The Korean Journal of Ecology
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    • v.27 no.2
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    • pp.73-77
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    • 2004
  • Movement of shorebirds for roosting was studied to find their response to insufficient roosting area on Ganghwa Island. It was taken from two kinds of aspects of population fluctuation and direct observation of movement from March to October in 2002. Based on the data from their weekly fluctuation and flight observation, shorebirds on Ganghwa Island moved to roosts located far away. Shorebirds feeding at southern Ganghwa Island moved to Yeongjong Island for roosting during the spring tide period. High tide count showed that the number of shorebirds on Yeongjong Island increased strikingly, while the number of birds on Ganghwa Island decreased. As the tide level increased, the number of shorebirds on Ganghwa Island decreased in the fall migrating season (r$_{s}$= -0.81, p<0.001), whereas that on Yeongjong Island was not correlated significantly. Direct observation showed that some of the birds on the upper tidal zone of Ganghwa Island moved directly to the northern mudflat of Yeongjong Island during the flowing tide or dropped by flat zone on Seondu-ri. Insufficient coastal wetlands on Ganghwa Island induced them to move away from the island for roosting place and to endure costly flight energy expenditure. The development of wetlands on the southern Yeongjong Island would make them have no place available to roosts. Therefore this study proposes that shorebird roosts on Ganghwa Island should be created to conserve their habitat.t.

Ecological Function Assessment for a Fishways of Geumgang Estuary Dike (금강하구둑 어도의 생태적 기능 평가)

  • Kim, Jae-Ok;Jang, Kyu-Sang;Shin, Hyun-Sang;Yang, Hyun;Jang, Jun-Ho
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.3
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    • pp.1-7
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    • 2010
  • The ichthyofauna and passing efficiency of fishways were surveyed in Geumgang estuary from May to October in 2009. The fishes collected were classified into 24 species, 23 genera belonging to 8 families. These 24 species consist of 17 freshwater fish species, 3 migration fish species and 4 peripheral freshwater fish species. Seasonal function of fishways showed the migration from May to June and returning to the reservoir of fishes be washed out to sea when sluice gate open by rainfall in July and August. Most of the fishes catched in fishways moved from middle tide to high tide except for July. Fishes ascended fishways between the middle ebb tide and the ebb tide only July, because small freshwater swim against the fishway for leaching the reservoir through the newly formed flow when the water level at the fishway kept dropping. Small fishes that body length less than 200 mm mainly used gabion type fishways and fishes over 200 mm utilized a cascade type fishways. Based on the total individuals collected, the efficiency of the fishway was 1 % for the anadromous fish and over 80 % for freshwater fish. Therefore, it is concluded that ecological function of the fishway in the Geumgang estuary dike be very important not only for fish migration but also freshwater fishes's returning.

The Evaluation of Water Quality in Coastal Sea of Saemangeum by Chemical Environmental factors (새만금 하구역의 이화학적 환경요인에 따른 수질 평가)

  • Kim, Jae-Ok;Kim, Won-Jang;Jo, Kuk-Hyun
    • Journal of The Korean Society of Agricultural Engineers
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    • v.49 no.5
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    • pp.57-65
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    • 2007
  • The objective of this study was to evaluate chemical water quality by hourly monitoring(25hr) of Saemangeum esturary. For this study, we selected 2 sites like a Mangyong Bridge(St. 6) and Dongjin Bridge(St. 7). Inflow of salt water was not detected during low tide(maximum 553, 508cm) of all stations, while the salinity rises were detected in spring tide(750cm). When 602m of maximum tide was reached, salinity concentration was increased at St. 7, while there was no change in St. 6. Therefore, We know that salinity variation is greatly influenced by tide height at survey site. Also, significant variance of salinity(p<0.05) was found between St. 6 and St. 7 because dike construction made the flood tide move into the Dongjin river. Total suspened solids(TSS) concentration was increased because of the river runoff at St. 6, and also the turbulance and resuspension according to salt intrusion at St. 7. During the high tide, the water discharge from the sea seemed to dilute the nutrient but to elevate TSS concentration in St. 7. Silicate and nitrate concentrations in the studied site were decreased by the mixing of sea water, whereas the evident trend of phosphate concentration was not found. This result can be explained by the phosphorus condition. Phosphorus exists inactive when it is affected by hydrated iron and adsorbed onto suspended matters. Compared to the environmental conditions of the St. 6 and St. 7, physical factors such as temperature, dissolved oxygen and TSS have statistically no significant difference(p<0.001), but nutrient concentrations were higher at St. 6 than St. 7. It could be suggested from these results that it is important to control the discharge of fresh water by sewage treatment plants located in St. 6 for water quality management.

Benefits of Camera Monitoring System in Studying on Coastal Dune Erosion by Typhoon (태풍으로 인한 해안사구 침식 연구에 대한 카메라 관측 시스템의 유용성)

  • Kim, Taerim;Kim, Dongsoo
    • Journal of The Geomorphological Association of Korea
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    • v.21 no.4
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    • pp.41-52
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    • 2014
  • Coastal dune, as one part of beach system, contributes for beach recovery as well as preventing beach erosion by exchanging sands between beach and dune. Due to high tidal range, the boundary of sand dunes on the west coast of Korean Peninsula is outside the high water line during spring tide and erosion also occurs in high waves during spring high tide. This paper investigates the erosion status of the dunes located in the JangHang beach by analyzing images from camera monitoring system, and tide and wave data observed adjacent to the study site during the passage of 4 typhoons in 2012. It also studies the benefits of camera monitoring images in investigating the dune erosion and analyzing coastal topographic changes.

Temporal and Spatial Fluctuations of Coastal Water Quality and Effect of Small Tide Embankment in the Muan Peninsula of Korea (무안반도 연안수질의 시ㆍ공간적 변동과 소규모 방조제의 영향)

  • Lee Dae-In;Cho Hyeon-Seo;Lee Gyu-Hyung;Lee Moon-Ok
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.6 no.4
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    • pp.24-36
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    • 2003
  • In this study, we estimated the seasonal fluctuations of water quality and effect of small tide embankment in coastal water around the Muan Peninsula, which is located in the northern part of Mokpo city, and layer farming ground is spread around there. Some physical and chemical factors were analyzed to characterize water quality from Jan. to Oct. in 1994. The results were as follows: Dissolved oxygen was slightly under saturation in the almost areas of July, and in some bottom layer at ebb tide of October. Distribution of COD showed high values that over 2㎎/L in October and flood tide of April by the discharge of freshwater and resuspension of benthic sediment, which exceeded water quality criteria II. Maximum values of dissolved inorganic nitrogen ware appeared in surface layer during the flood tide of October, while minimum of that showed in surface layer in April. Concentration of dissolved inorganic phosphorus was higher at July than the others, which ranged from 0.24 to 2.08㎍-at/L. Mostly mean values of N/P ratio were lower than 16, it mean that nitrogen is more limiting nutrient than phosphorus for the growth of phytoplankton. The values of eutrophication index were in the range of 0.07~0.81. However, very high values due to increase of COD were estimated near the tide embankment and southern part in relation to tidal current in October. Water quality around tide embankment was suddenly changed worse within a short period after opening the water gate during the rainfall.

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Environmental Condition and Microbial Survey of the Tide Pools Densely Inhabited by Tigriopus japonicus MORI (동물성 플랑크톤 Harpacticoid, Tigriopus japonicus MORI가 서식하는 Tide Pool 생태계의 조사)

  • LEE Won Jae;TAGA Nobuo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.18 no.1
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    • pp.57-62
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    • 1985
  • The three tide pools of Kanagawagen Aburatsubo coast, Japan were studied for 5 months (June-October, 1991) to know the physicochemical factors and changes of the microflora, In the tide pools salinity was ${\simeq}35\%0$, temperature range was $14{\sim}32^{\circ}C$ and pH range was $7.4{\sim}8.9$. Particulate organic carbon (POC) was $255{\sim}3980\;{\mu}g-at/l$, and total phosphate-P was $1.0{\sim}27.0\;{\mu}g-at/l$. The numbers of suspended bacteria and heterotrophic bacteria on the algae were $10^4{\sim}10^7/ml$ and $10^6{\sim}10^8/g$, respectively. Bacterial flora isolated from the Samples were Acinetobacter spp., Moraxella spp., Flavobacterium spp. and Pseudomonas spp., While Acinetobacter spp. was predominant among them. T. japonicus occurred dominantly with densities of $2200{\sim}7000/l$ during $August{\sim}september$. During this period the sharp increases of the unicellular microalgae and the protozoans were observed. According to the experimental results (POC, total phosphate-P, numbers and composition of bacterial flora), T. japonicus seemed to inhabit the environment with high eutrophication and high variability.

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Impacts of Local Meteorology caused by Tidal Change in the West Sea on Ozone Distributions in the Seoul Metropolitan Area (서해 조석현상에 따른 국지기상 변화가 수도권 오존농도에 미치는 영향)

  • Kim, Sung Min;Kim, Yoo-Keun;An, Hye Yeon;Kang, Yoon-Hee;Jeong, Ju-Hee
    • Journal of Environmental Science International
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    • v.28 no.3
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    • pp.341-356
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    • 2019
  • In this study, the impacts of local meteorology caused by tidal changes in the West Sea on ozone distributions in the Seoul Metropolitan Area (SMA) were analyzed using a meteorological model (WRF) and an air quality (CMAQ) model. This study was carried out during the day (1200-1800 LST) between August 3 and 9, 2016. The total area of tidal flats along with the tidal changes was calculated to be approximately $912km^2$, based on data provided by the Environmental Geographic Information Service (EGIS) and the Ministry of Oceans and Fisheries (MOF). Modeling was carried out based on three experiments, and the land cover of the tidal flats for each experiment was designed using the coastal wetlands, water bodies (i.e., high tide), and the barren or sparsely vegetated areas (i.e., low tide). The land cover parameters of the coastal wetlands used in this study were improved in the herbaceous wetland of the WRF using updated albedo, roughness length, and soil heat capacity. The results showed that the land cover variation during high tide caused a decrease in temperature (maximum $4.5^{\circ}C$) and planetary boundary layer (PBL) height (maximum 1200 m), and an increase in humidity (maximum 25%) and wind speed (maximum $1.5ms^{-1}$). These meteorological changes increased the ozone concentration (about 5.0 ppb) in the coastal areas including the tidal flats. The increase in the ozone concentration during high tide may be caused by a weak diffusion to the upper layer due to a decrease in the PBL height. The changes in the meteorological variables and ozone concentration during low tide were lesser than those occurring during high tide. This study suggests that the meteorological variations caused by tidal changes have a meaningful effect on the ozone concentration in the SMA.

Short-term Variation in Species Composition of Surf-zone Fishes at Daechon Beach, the Yellow Sea of Korea (대천 해빈 쇄파대어류 종조성의 단기 변화)

  • Lee, Tae-Won
    • Korean Journal of Ichthyology
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    • v.13 no.1
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    • pp.32-39
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    • 2001
  • Surf-zone fishes in Daechon Beach, situated at the mouth of Cheonsu Bay, Korea, were collected by a beach seine during the spring and neap tides in August 1999. Short-term variation in species composition was analyzed based on tidal range, tidal level, and time of day. Of 24 species identified, juvenile pelagic fishes predominated in the number of individuals captured. Wilcoxon signed-rank test revealed that the number of individuals was significantly higher during the spring tide than during the neap tide. During the spring tide the fishes were more abundant at the low level than at the high level, while during the neap tide there was no significant difference. The mean density of pelagic fishes did not show significant differences between high and low tides. Demersal fishes were caught mainly in the water below the low level of the neap tide.

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