• Title, Summary, Keyword: High tide

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Tidal Currents In The Channel Near Incheon Harbour (인천항부근 수로의 조류)

  • Bong, Jong Hon
    • 한국해양학회지
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    • v.13 no.1
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    • pp.29-34
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    • 1978
  • Simultaneous tidal current observation at five or seven stations on the channel near Incheon Habour was conducted at neap, mean and spring tides during the period of August 16 to August 27, 1976 and the characteristic of tidal currents with each tide was studied by the analysis of these data. Times of slack refer to the times of high and low waters at neap, mean and spring tides seem to be small. Times of maximum current refer to the times of high and low waters at the mean tide tends to appear earlier than that of the neap tide and later than that of the spring tide. The velocity ratio of maximum ebb current to maximum flood current at the mean tide has larger value than that of neap tide and has smaller value than that of spring tide. The current velocity ratio of spring tide to neap tide and to mean tide are approximately 1.8 and 1.3, respectively.

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Statistical Analyses on the Relationships between Red Tide Formation and Meteorological Factors in the Korean Coastal Waters (한국 연안의 적조형성과 기상인자간의 관계에 대한 통계적 해석)

  • 윤홍주;서영상;정종철;남광우
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.4
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    • pp.926-932
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    • 2004
  • This study deals with the statistical analyses on the relationship between the red tide formation and the meteorological factors in the Korean coastal waters. From 1995 to 2002, the red tide was observed every year and the number of occurrences increased as well. The red tide mostly occurred in July, August, September and October. from multiple linear regression, the meteorological factors governing the mechanisms of the increase in the number of red tide occurrences are found to be a water temperature, rainfall, sunshine duration and wind velocity. But water temperature as the limited factor controlling the growth of phytoplankton (Cochlodinium polykrikoids) in 15∼$30^{\circ}c$. NO = 8.089 - 0.319WT + 0.019RF + 0.141SD + 0.l19WV (R = 0.897) in August NO = 7.531 - 0.327WT + 0.027RF + 0.208SD + 0.208WV (R = 0.894) in September Here, NO is the number of occurrence for red tide, WT is water temperature, RF is rainfall, SD is sunshine duration and WV is wind velocity, respectively. The necessary times till the day of red tide occurrence verse the day when water temperature reaches $15^{\circ}c$ are 78∼104 days, then it should be divided the coastal waters into 4 areas by the comparison among the accumulated sunshine duration, water temperature and rainfall as follows; the South West Coast (SW), South Middle Coast (SM), South East Coast(SE) and East South Coast (ES). The coastal areas that red tide occurs were complicated and various by change of marine environments. Usually red tide with a high concentrations (individual number, cells/ml) appeared in SM and SE. It was found that the general situations for the frequencies of red tide formation are mainly concentrated to 24.5∼$25^{\circ}c$ (high water temperature) and eve. 1000 cells/ml (high individual number) such as the category of red tide warning.

Satellite monitoring and prediction for the occurrence of the red tide in the coastal areas in the South Sea of Korea - I. The relationship between the occurrence of red tide and the meteorological factors

  • Yoon, Hong-Joo;Kim, Young-Seup;Kim, Sang-Woo
    • Proceedings of the KSRS Conference
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    • pp.656-656
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    • 2002
  • It is studied on the relationship between the occurrence of red tide(Chlorophyll-a concentration by the in-situ and satellite data) and the meteorological factors (precipitation, air temperature, sunshine and winds) in the coastal areas in the South Sea of Korea. In summer and early-fall which frequently occurred the red tide, the precipitation above 213mm had directly influence on the occurrence of red tide because it carried the nutritive substance which originated from the land into the coastal areas. Then air temperature kept up generally high values as 23~26$^{\circ}C$, and sunshine with 187~198hours and wind velocity with 3.1~7.9m/s showed not directly the relationship on the occurrence of red tide.

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COMPARISON OF RED TIDE DETECTION BY A NEW RED TIDE INDEX METHOD AND STANDARD BIO-OPTICAL ALGORITHM APPLIED TO SEA WIFS IMAGERY IN OPTICALLY COMPLEX CASE-II WATERS

  • Shanmugam Palanisamy;Ahn Yu-Hwan
    • Proceedings of the KSRS Conference
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    • pp.445-449
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    • 2005
  • Various methods to detect the phytoplankton/red tide blooms in the oceanic waters have been developed and tested on satellite ocean color imagery since the last two and half decades, but accurate detection of blooms with these methods remains challenging in optically complex turbid waters, mainly because of the eventual interference of absorbing and scattering properties of dissolved organic and particulate inorganic matters with these methods. The present study introduces a new method called Red tide Index (Rl), providing indices which behave as a good measure of detecting red tide algal blooms in high scattering and absorbing waters of the Korean South Sea and Yellow Sea. The effectiveness of this method in identifying and locating red tides is compared with the standard Ocean Chlorophyll 4 (OC4) bio-optical algorithm applied to SeaWiFS ocean imagery, acquired during two bloom episodes on 27 March 2002 and 28 September 2003. The result revealed that OC4 bio-optical algorithm falsely identifies red tide blooms in areas abundance in colored dissolved organic and particulate inorganic matter constituents associated with coastal areas, estuaries and river mouths, whereas red tide index provides improved capability of detecting, predicting and monitoring of these blooms in both clear and turbid waters.

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The Analysis of Tidal Effect on Stress-Strain Behavior in the Boundary Surface of Sea Dike Embankment (조석현상이 방조제 경계면의 응력-변형 거동에 미치는 영향 분석)

  • Eam, Sung Hoon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.55 no.2
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    • pp.1-8
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    • 2013
  • This study was performed for the purpose of analyzing the effect of tide on the stress-strain behavior in the boundary surface of sea dike embankment. Tide is a dynamic condition, but there are not suitable numerical models to solve the dynamic embankment condition caused by tide. So the analysis was simplified to quasi dynamic as follow. First, seepage by tide was analyzed according to elapsed time, and the results of the analysis at every hour during one periodic cycle time of 12 hours were applied to the pore water pressure conditions of stress-strain analysis with hyperbolic model by Duncan and Chang. The place at which maximum shear strain took place in the analysis result moved up and down repeatedly along the boundary of the dredged sand fill section and the crashed stone filter section. The value of maximum shear strain was large at high water level of tide. This result means that contraction and relaxation occur in turn repeatedly at every specific position along the boundary, and the repeated action compact loose position with sand moved down from the upper position by gravity. The experiment with the small sea dike model showed the result consistent with the numerical analysis. The surface of sea side on the dike collapsed at high water level after a couple of repetition of the rising and falling of water.

The Distribution and Behaviors of Suspended Matters in Seomjin River Estuary - Compared with Rainy and Wet Season - (섬진강하구에서 부유물질의 분포와 거동 - 풍수기와 평수기의 비교 -)

  • Kim, Seok-Yun;Lee, Byoung Kwan
    • Journal of Korean Society on Water Environment
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    • v.25 no.6
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    • pp.935-942
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    • 2009
  • During period of the rainy season of spring tide Aug. 2005, the suspended sediment transport rate from Seomjin River increased ten times as high as neap tide of low river discharge. During ebb tide of high terrestrial input, the grain size of suspended particles of both surface and bottom layer of the water column, showed a uni-modal distribution with a dominant peak at coarse fraction, which suggests a characteristic development of floc-sized particles of low mean effective density. On the contrary, the particles supplied toward upstream of Seomjin river from Gwangyang Bay during flood tide showed a bi-modal distribution with a secondary peak at finer fraction, possibly due to the resuspension and the deflocculation associated with the increased shear velocity at near bottom. Break-up of large flocs is also suggested by the increased mean effective density. However, settling velocity was lower during flood tide because of smaller grain size. Thus, net deposition of suspended sediment is expected at within Gwangyang Bay instead of upstream of Seomjin River, even though suspended sediment transport rate at near bottom water was three times higher than that at surface water during flood tide.

Wave Control by Tide-Adapting Submerged Breakwater (조위차 극복형 잠제의 파랑제어)

  • Lee, Woo-Dong;Jeong, Yeon-Myeong;Hur, Dong-Soo
    • Journal of Ocean Engineering and Technology
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    • v.33 no.6
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    • pp.573-580
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    • 2019
  • A submerged breakwater is a coastal structure built under water with excellent landscape. The depth of the crest of the breakwater should be maintained at more than a certain level in order for the submerged breakwater to control waves properly. This means that the effect of blocking waves deceases sharply at high tide in coastal areas with large tidal differences. In this study, we proposed a Tide-Adapting Submerged Breakwater (TA-SB) to overcome this problem, and then we conducted hydraulic model experiments to evaluate the performance of the TA-SB for controlling waves. The experimental results showed that the tapered wings attached to the crest of the TA-SB helped induce forced breaking waves. In particular, they were very effective in blocking waves and attenuating wave energy at high tide. In addition, the wave control performance of the proposed TA-SB was far superior to the Tide-Adapting Low-Crested Structure (TA-LCS) of the previous study.

A Study of sea Dike meterials loss due to Scouring and Consolidation Settlement During the Periond of Construction on Construction on the West Cost of Korea (서해암 방조제 공사 기간중 유실토량 측정시험)

  • 안재숙
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.14 no.1
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    • pp.2503-2519
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    • 1972
  • The studies were carried out to find the cause and the quantitative evaluation of sea dike materials loss which is occured during the period of construction works for the tideland reclamation projects on the west coast of Korea. Major subjects to studies were to establish the typical relationships between the tidal flow and the movement of dike materials, the tidal-flow and the erosion, the dike materials and the ratio of material movement(losses), construction methods and the ratio of materials movement (losses). Based on the above subjects, the studies were made for the purpose of obtain the following informations; (1) Collecting and evaluaing the data of dike material losses due to foundation settlement, from designed existing dikes on the west coast. (2) By the field investigation at A-San Sea Dike, Pyong Taek Project, the Comparison would be made by the relationships between the tide velocity and the movement of dike foundation under the natural conditions and the period of construction so that find out the relationship between the dike materials of foundation situation and settlements. With regard to the dike construction works, it is so difficult to calculate the exact quantity of material losses due to the foundation settlements. The major factors that affect the settlement losses of the dike materials are: (1) Topographical variation (2) Swepting the sectional area of dike by the tide velocity. (3) Dumping riprap to the outerside of dike during the period of construction works. (4) Sectional area losses by the cause of occurence of the new tide channels. (5) material losses by the heavy storms. (6) Consolidation settlement by the foundation weakness. (7) Material losses by the earth materials by tide flow. Most hi호 material losses were occured by the Consolidation settlement due to the foundation weakness, the maximum tide velocities due to decrease the cross sectional area of the gaps and erosion of foundation due to the range of tide, Inner and outerside of dike, or dike material loses due to the tide flow. Final conclusion would be obtained by the continuous measurement of consolidation settlement at the stage of final clusure of the dike. (It is scheduled to close on the end of 1972) However, intermediate conclusion can be introduced as follows: (1) The estimation of material(losses) during the period of construction works for the existing sea-dikes up to date were only empirical. The material losses at the general closure for design was estimated at 10% of the riprap, 20% of the earth materials, and 20% of the riprap, 40% of the earth materials at the final closure of the dike. The final closure estimated double quantity to the general closure, but it is still doubt. (2) The ratio of consolidation settlements was found smaller than the calculated quantity. It can be foreseen that settlement speeds is higher thom the calculated speeds. (3) The movement of dike foundation under the natural conditions were not so depends on the geological conditions of the foundation. (4) When the tide velocities was estimated 100 at the normal tide, it was estimated 125 at the high tide and 55 at the low tide. The tide velocities at the low tide shows apparently lower than the high tide and the higher velocities at the deep water depth.

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Effect of the Freshwater Discharge on Water Quality Variation and in Haechang Bay, Korea (해창만의 수질환경변동 및 담수방류의 영향평가)

  • Lee, Dae-In;Cho, Hyeon-Seo;Lee, Moon-Ok
    • Journal of Environmental Impact Assessment
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    • v.12 no.5
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    • pp.341-348
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    • 2003
  • Seasonal characteristics of water quality and effect of the freshwater discharge during open the tide embankment in Haechang Bay were evaluated. In the freshwater, where interior of the tide embankment, COD and Chl-a exceeded about 4mg/L and $10mg/m^3$, respectively, independent of season, while in the seawater they showed high values in April and July in contrast to the other period due to input of freshwater and increase of phytoplankton, respectively. The content of seawater inorganic nitrogen maintained a relatively high level at inner part of the bay, whereas high values of inorganic phosphorus content was distributed at all over the bay. The limiting factor for algal growth was nitrogen with respect to the N/P ratio. The compass of influence by the freshwater discharge in April was quite different with water pollutants. As a result of the salinity variation with time, the freshwater extended strongly to offshore from the surface layer without mixing with depth when open the tide embankment, and reached within about one hour at a station which is 3.5km from the tide embankment. To effective water quality management of Haechang Bay, discharge rate and pollutant loads should be controlled.

Comparison of Topex/poseidon Sea Surface Heights with Tide Gauge Sea Levels in the South Indian Ocean (남인도양에서의 Topex/Poseidon sea surface heights와 tide gauge sea levels간의 비교)

  • YOON Hong-Joo
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.32 no.3
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    • pp.368-373
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    • 1999
  • Topex/Poseidon sea surface heights are compared to tide gauge sea levels in the South Indian Ocean in the period of January 1993 to December 1995. A user's handbook (AVISO) for processing sea surface height data was used in this study. Topex/Poseidon sea surface heights were obtained from satellite data at the proximity of tide gauge stations. These data were reproduced by a linear interpolation with the interval of 10 days and were processed by the Gaussian filter with a 60-day window. The tide gauge sea levels were obtained in the same manner as the satellite data. The main results on RMS (Root-Mean-Square) and CORR (CORRelation coefficient) in our study were shown as follows: 1) on the characteristics between two data (in-situ and model data), the results (RMS=2.96 cm & CORR=$92\%$ in the Amsterdam plateau, and RMS=3.45 cm & CORR=$59\%$ in the Crozet plateau) of the comparison of Topex/Poseidon sea surface heights with tide gauge sea levels, which was calculated by in-situ data of obsewed station showed generally low values in RMS and high values in CORR against to the results (RMS=4.69 cm & CORR=$79\%$ in the Amsterdam plateau, and RMS= 6.29 cm & CORR= $49\%$ in the Crozet plateau) of the comparison of Topex/Poseidon sea surface heights with tide gauge sea levels, which was calculated by model data of ECMWF (European Center for Medium-range Weather Forecasting), and 2) on the characteristics between two areas (Kerguelen plateau and island), the results (RMS=3.28 cm & CORR= $54\%$ in the Kerguelen plateau) of open sea area showed low values in RMS and high values in CORR against to the results (RMS= 5.71 cm & CORR=$38\%$ in the Kerguelen island) of coast area, respectively.

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