• Title, Summary, Keyword: tidal and seasonal variations

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Seasonal Variations of Temperature and Salinity in Incheon Coastal Area (인천 연안역의 수온 및 염분의 계절 변화)

  • 최용규;신문섭;이병걸
    • Journal of Environmental Science International
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    • v.9 no.2
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    • pp.131-136
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    • 2000
  • The seasonal data obtained at National Fisheries Research and Development Institute from 1989 to 1994 were analyzed to investigate the seasonal variations of temperature and salinity in incheon coastal area. In the tidal flats covering from Incheon harbor to Sorae, the mean temperatures are higher, the amplitudes of flats, the mean salinities are lower, its amplitudes are larger, and its phases are later than those of outer tidal flats. These suggest that Inchion coastal area may be divided into two areas: the tidal flats from Incheon harbor to Sorae, which is largely influenced by the seasonal variation of solar heating, precipitation and evaporation and the outer tidal flats, which is slightly influenced by the effects of seasonal variation of salinity.

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Seasonal Variations of Chemical Composition of the Estuary Water in Guang Yang Inlet from Mar. 1961 to Feb. 1962 (蟾津江 河口 干潟地 水質의 年間變化)

  • Won, Chong-Hun
    • Journal of the Korean Chemical Society
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    • v.6 no.2
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    • pp.176-197
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    • 1962
  • Seasonal variations of chemical constituents of estuarine water at a definite station of the tidal flat in Guang Yang inlet have been determined for two days a month. The range and mean of the annual variations are as follows:Tidal variations through a year are as follows:1. Although the tidal value of pH is almost constant during one tidal cycle, it raises abruptly 0.1-0.2 intervals of pH value during the first period of flood.2. The lower values of chlorinity, magnesium and calcium contents have been determined the nearer the slack after ebb, and slightly higher during the first period of flood tide than the last of ebb. The tidal change of calcium contents is more remarkable than of magnesium.3. The higher per cent saturation values of dissolved oxygen, sometimes higher than 100 per cent, re determined the nearer the slack after ebb.4. The total nitrogen contents, relatively poor, varies accidentally during one tidal cycle, whereas phosphate-P and silicate-Si are rich at the slack after ebb and increase proportionally to the mixing percentage of fresh water. The average values, 52.2 and 18.5 of Si/P and N/P are greater than of the normal.5. The acid soluble iron contents, lower in winter than in summer, is also varies accidentally during one tidal cycle and the magnitude of the variation is large.6. The chemical composition considered from the value of Ca/Cl or Mg/Cl of estuarine water varies according to the chlorinity even at the high chlorinity of 18-19%.

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Seasonal Variation and Preservation Potential of Tidal-Flat Sediments on the Tidal Flat of Gomso Bay, West Coast of Korea

  • Chang, Jin-Ho
    • The Korean Journal of Quaternary Research
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    • v.18 no.2
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    • pp.19-22
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    • 2004
  • Seasonal changes of topograpy, sediment grain size and accumulation rate on the Gomso-Bay tidal flat(Fig. 1), west coast of Korea, have studied in order to understand the seasonal accumulation pattern and preservation potential of tidal-flat sediments. Seasonal levelings across the tidal flat show that the landward movement of both intertidal sand shoals and cheiers accelerates during the winter and typhoon period, but it almost stops in summer when mud deposition is instead predominant on the middle to upper tidal flat. Seasonal variations of mean grain size were largest on the upper part of middle tidal flat where summer mud layers were eroded during the winter and typhoon periods(Fig. 2). Measurements of accululation depths from sea floor to basal plate reveal that accumulation rates were seasonally controlled according to the elevation of tidal-flat surface(Table 1) : the upper flat, where the accumulation rate of summer was generally higher than that of winter, was characterized by a continuous deposition throughout the entire year, whereas on the middle flat, sediment accumulations were concentrated in winter realtive to summer, and were intermittently eroded by typhoons. The lower tidal flat were deposited mostly in winter and eroded during summer typhoons. Cancores taken across the tidal flat reveal that sand-mud interlaers resulting from such seasonal changes of energy regime are preserved only in the upper part of the deposits and generally replaced by storm layers downcore(Fig. 3). Based on above results, it is suggested that the storm deposits formed by winter stors and typhoons would consist of the major part of the Gomso-Bay deposits(Fig. 4).

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Seasonal and Spatial Variations of Tidal Flat Sediments in Yeoja Bay, South Coast of Korea (한국 남해안 여자만 조간대 퇴적물의 시공간적 변화)

  • Choi, Jeong-Min;Lee, Yeon-Gyu;Woo, Han-Jun
    • Journal of the Korean earth science society
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    • v.26 no.3
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    • pp.253-267
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    • 2005
  • Seasonal and spatial variations of tidal flat sediments were studied in Yeoja Bay. Results of the yearly observation of tidal flat transect lines indicated that the monthly change of grain size composition was not distinct from each tidal flat transect line, but it was quite clear that clay covered $40\~70\%$ of the sediment composition. Clay composed most highest in the northern part of the bay, and lowest in the western. As clay content increased, water and organic matter showed a tendency of increase, while the mean grain size was fixed per clay amount. Shear strength came out as 0 kPa as a whole. Seasonal variations of clay contents in each tidal flat were higher in winter and spring, but lower in summer and autumn. Thefine sediments were likely to be accumulated in the winter and spring. The average accumulation rate of each tidal flat was $-14.62\~38.57mm{\cdot}yr^{-1}$. The numbers showed $32.13mm{\cdot}yr^{-1}$ in the northern, $-14.62mm{\cdot}yr^{-1}$in the western, and $6.46mm{\cdot}yr^{-1}$ in the eastern part. During the coarse of this study sediment accumulation rates indicated that the sediments deposited continuously in the northern part of tidal flat, whereas erosion occurred in the western part. However, there was no distinct change in the eastern part. It was due to the clockwise lateral circulation in Yeoja Bay. Seasonally, sedimentation happened during the dry season (winter and spring) and erosion during the wet season (summer and autumn).

Seasonal Variation Patterns of Tidal Flat Sediments in Semi-enclosed Hampyong and Kwangyang Bays, West and South Coasts of Korea (한반도 서해안과 남해안의 반페쇄된 만에서 조간대 퇴적물의 계절변화에 관한 비교 연구: 서해안의 함평만과 남해안의 광양만)

  • Ryu, Sang-Ock
    • Journal of the Korean earth science society
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    • v.24 no.6
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    • pp.578-591
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    • 2003
  • To investigate the seasonal variation patterns of tidal flat sediments in semi-enclosed Hampyong and Kwangyang Bays, respectively west and south coasts of Korea, accumulation rate and grain-size in the sediments were monitored during 2${\sim}$4 years. The mud flats in the northern and eastern parts of Hampyong Bay were eroded in summer and deposited in winter, but mixed flats in the southern part of the bay show reversed seasonal variations to the mud flats. These variations are most likely connected with wave actions induced by monsoon and physiographic setting of the tidal flats in the bay. In contrast, the tidal flats of Kwangyang Bay were eroded in summer and deposited in other seasons except summer, different from the case of Hampyong Bay. The physiography of Kwangyang Bay are characterized by dominant flood tides and weak wave actions. However, in summer, the surface sediments were abruptly eroded by occasional typhoons and heavy rainfall. These weather conditions appear to be important factors to accelerate erosion on the tidal flat in semi-enclosed bays, south coast of Korea.

Seasonal Variations of Near-Field Dilutions of Submerged Multiport-Diffuser Discharges in Masan Bay (마산만 수중 방류수의 계절별 근역희석률 변화)

  • 강시환;박광순
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.11 no.2
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    • pp.116-126
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    • 1999
  • In this paper, we have studied the seasonal vanatIons of near-field dilutions of wastewater discharged from the submerged mutiport-diffuser in Masan Bay. Seasonal changes of temperature and salinity, and tidal currents were measured at 16 stations in Masan Bay. Based on the observed ambient field data, the seasonal changes of near-field dilutions due to ambient current and density fields were calculated by CORMIX model. Because of the shallow ambient water depth of 15 m, the density profiles are isopycnal in autumn and winter seasons, in which the dilution factors were the highest, 168 with the strong spring-tidal current and 110-120 with the weak neap-tidal current. As the season changes from spring to summer, the dilution factors are considerably reduced by the factor of 2 as the thermocline is getting deepened up to Sm in depth in summer. In the case of a weak ambient current, the dilution factor in summer was reduced to 1/4 of the dilution in winter. However, with strong ambient current the difference between summer and winter dilutions becomes relatively small by 30%. The results indicate that the seasonal variation of near-field dilution is very large up to 4 times with a weak neap-tidal current, but its variations become small under a strong ambient current of spring tide in MasanBay.

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Long-Period Sea Level Variations around Korea, Japan, and Russia (우리나라 근해의 장기적인 해수면변화)

  • PANG Ig-Chan;OH Im-Sang
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.27 no.6
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    • pp.733-753
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    • 1994
  • Monthly mean sea levels from 103 tidal stations in Korea, Japan, and Russia are analyzed to study long-period sea level variations. Barometric adjustment are done for all the sea level data, using monthly air pressures at sea levels from meteorological stations near tidal stations. Seasonal variation is dominant in most of study area. It is the largest in the coasts along the Tsushima Current, and the smallest in the Russian coasts. The cross-correlations of seasonal variations are very high between the coasts along the Tsushima Current. In these marginal seas, seasonal variations seem to be related with the Tsushima Current. The phase of seasonal variations is generally getting late from south to north, and also from west to east. On the other hand, longer-period variations(longer than seasonal variation) have the largest amplitudes and the earliest phases in the coasts along the Pacific Ocean, which shows that they propagate from the Pacific Ocean. Shorter-period variations (shorter than seasonal variation) have generally lower cross correlations. Their values do not show any dictinct difference between areas, and show a common tendency that they are inversely proportional to distance. It implies that the shorter period waves are generated all over the study areas, and propagate in all the directions with faster dissipations. The trends of sea levels in the study area are generally negative in the coasts along the Pacific Ocean and positive in the other areas during the period of 1965 to 1985. By the trends, the mean volume transport between Cheju and Sasebo can be reduced by about 1 Sv during the period. The seasonal variation of volume transport obtained by sea level difference is about 2 Sv in the Korea Strait. The values are comparable to previous reports.

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Seasonal Accumulation Pattern and Preservation Potential of Tidal-flat Sediments: Gomso Bay, West Coast of Korea (조간대 퇴적물의 계절적 집적양상과 보존: 한국 서해안의 곰소만)

  • Chang, Jin-Ho;Choi, Jin-Yong
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.3 no.3
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    • pp.149-157
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    • 1998
  • Seasonal changes of topography, sediment grain size and accumulation rate in the Gomso-Bay tidal flat, west coast of Korea, have been studied in order to understand the seasonal accumulation pattern and preservation potential of the tidal-flat sediments. Seasonal levelings across the tidal flat show that the landward movement of both intertidal sand shoals and cheniers accelerates during the winter and typhoon periods, but it almost stops in summer when mud deposition is instead predominant at the middle and upper tidal flats. Seasonal variations of mean grain size were largest on the upper part of middle tidal flat where summer mud layers were eroded during the winter and typhoon periods. Measurements of accumulation depths from sea floor to basal plate reveal that accumulation rates were seasonally controlled according to the elevation of tidal-flat surface. The upper tidal flat where the accumulation rate of summer was generally higher than that of winter was characterized by a continuous deposition throughout the entire year, whereas in the middle tidal flat, sediment accumulations were concentrated in winter relative to summer and were intermittently eroded by typhoons. The lower tidal flat were deposited mostly in winter and eroded during summer typhoons. Can cores taken across the tidal flat reveal that sand-mud interlayers resulting from such seasonal changes of energy regime are preserved only in the upper part of the deposits and generally replaced by storm layers downcore. Based on above results, it is suggested that the storm deposits by winter storms and typhoons would consist of the major part of the Gomso-Bay sediments.

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Cyclic Change of Phytoplankton Community in Mankyeong River Estuary prior to the Completion of the Saemankeum Seawall (새만금 방조제 완공 이전 만경강 하구역 식물플랑크톤 군집의 주기적인 변동)

  • Kim, Young-Geel;Park, Jong-Woo;Jang, Keon-Gang;Yih, Won-Ho
    • Ocean and Polar Research
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    • v.31 no.1
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    • pp.63-70
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    • 2009
  • Eutrophicated water fed through Mankyeong River and Dongjin River into the new Saemankeum Lakemight seriously affect the water quality and phytoplankton community in the lake. To obtain control reference data for the later studies on environmental changes due to the construction of the Saemankeum Sea Wall, we performed a monthly investigation on the physico-chemical properties of the water and phytoplankton community at 3 stations in the Mankyeong River Estuary over 14 months starting from September 1999. Water temperature ranged from $0.3{\sim}32.9^{\circ}C$ due to the typical seasonal variations in temperate on the coasts and salinity exhibited a wide annual range of $0.2{\sim}33.7$ psu along with regular and huge hourly variations according to tidal cycles. Inorganic nutrients were supplied from rivers to the monitoring station and the whole lake. The average concentration of total-N, $6.99\;mg{\cdot}l^{-1}$, was higher than the water quality for agricultural use with peak values occurring in winter. Species composition showed a seasonal succession pattern, where a high diversity was observedin summer and autumn and vice versa in winter. Hourly variations of water properties in the "Mankyeong bridge" Station were quite regular and well in accordance with the daily tidal cycles. The different degree of sea water intrusion during the flood tide at each of the 3 stations exhibited a different range and variation pattern of water temperature and salinity throughout a day. Hourly changes in species composition were in harmony with the daily tidal cycles, resulting in extremely variable spatio-temporal variation.

Seasonal Variations of Physical Conditions and Currents in the Sea Near Gadeok-Sudo (가덕수도 근해에서 물리적 현상과 해류의 계절 변동)

  • Jang, Sung-Tae;Jeon, Dong-Chull;Shin, Chang-Woong
    • Ocean and Polar Research
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    • v.30 no.1
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    • pp.33-46
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    • 2008
  • In order to investigate seasonal variations of the physical environments in the region of Jinhae Bay-Nakdongpo, we carried out hydrographic surveys from November 2000 to November 2001. Horizontal and vertical distribution of salinity and temperature shows large seasonal variations. Water column is well mixed in winter and stratified in summer. Low-salinity water is distributed in the form of patches because of the drainage control at the Nakdong River. Seasonal variations in the sea near Gadeok-Sudo are affected by topography, river discharge and tidal current. Currents have been measured using a bottom mounted ADCP and DCM12 between November 2000 and August 2001 in the Gadeok-Sudo. The current in the Gadeok-Sudo shows a distinct two-layer structure with reversed current. Low-pass filtered time series of wind, sea elevation and current are coherent for the period of 1-2 days and are attributed to Ekman-like dynamics. Spatial and temporal circulation pattern shows a slight different. The subtidal current in Jinhae Bay goes northward, however is reversed in the Gadeok-Sudo mouth.