scholarly journals CURRENTS IN TIDAL FLATS DURING STORM SURGES

1976 ◽  
Vol 1 (15) ◽  
pp. 56
Author(s):  
Harald Gohren
Keyword(s):  
Tidal Flat ◽  
High Tide ◽  
Storm Surges ◽  
Water Layer ◽  
Tidal Flats ◽  
Coastal Engineering ◽  
Sand Transport ◽  
Engineering Problems ◽  
Aerial View ◽  
Strong Winds

Wind action in the viewpoint of coastal engineering is mainly a topic for discussions or investigations of waves, breakers, storm surges, sand transport on beaches and so on. Offshore currents, generated by wind shear stress concern more the scientific field of oceanographers. But in shallow coastal water wind induced drift currents indeed may be important for coastal engineering problems, as sediment transport, sewage spreading, salinity and so on. For example, along the German North Sea Coast (Fig. 1) we have a rim of extended tidal flats, built up by sand and mud and covered only by a water layer of 1 to 2 m at high tide. At low tide sands and mud flats fall dry. Fig. 2, an aerial view, gives an impression of a typical tidal flat, the "Neuwerker Watt" at the south side of the Elbe Estuary. The distance between main land and the sea side border of the flat is here about 20 km. A lot of investigations have been carried out here - initiated by a harbour planning task - giving some interesting results about currents in the tidal flat area during strong winds and storm surges. For the current measurements a recording current meter (Fig. 3) has been used, fixed at a tripod aluminum frame in 40 cm above bottom. The propeller meter starts at velocities of 5 cm/s. Tests in a flume proved that orbital currents give no disturbance if unidirectional currents of a certain magnitude are superimposed.

What ecological role do soft-substrate tide pools play for fishes? Difference in community structures between estuarine and coastal tidal flats in subtropical Japan

2020 ◽  
Vol 71 (7) ◽  
pp. 737
Author(s):  
Taiga Kunishima ◽  
Katsunori Tachihara
Keyword(s):  
Tidal Flat ◽  
High Tide ◽  
Tidal Flats ◽  
Individual Species ◽  
Nursery Ground ◽  
Ecological Role ◽  
Soft Substrate ◽  
Use Patterns ◽  
Habitat Value ◽  
Ecological Roles

Soft-substrate tide pools are considered important habitats for fishes from an ecological perspective. However, the ecological roles of such pools and use patterns by fish remain unclear, especially regarding differences between estuarine and coastal tidal flats. In this study, quantitative sampling using the quadrat method was performed in the estuarine and coastal tidal flats on Okinawa-jima Island of subtropical Japan during four seasons. Ecological roles of soft-substrate tide pools were classified as follows: (1) permanent habitat for residents; (2) nursery ground for transients; and (3) waiting area until high tide for accidental species. Within these classifications, the ecological role and value of tide pools for transient fishes varied between the tidal flat types. The habitat value of tide pools is higher for residents than for transient species because the habitat is not replaceable for residents because of their specific ability to survive there. By contrast, transient and accidental species use the tide pools as temporary habitats; however, their high diversity affects the variation in community structure on Okinawa-jima Island. Our results suggest that we should consider not only species diversity, but also habitat use patterns of individual species, together with their life history, when evaluating habitat value with regard to conservation and management of each tidal flat.

scholarly journals DYNAMIC WAVE SETUP

1988 ◽  
Vol 1 (21) ◽  
pp. 74 ◽  
Author(s):  
Jen-Men Lo
Keyword(s):  
Wave Spectrum ◽  
Low Frequency ◽  
Storm Surges ◽  
Coastal Engineering ◽  
Radiation Stress ◽  
Steady Wave ◽  
Wave Setup ◽  
Engineering Problems ◽  
Stress Term ◽  
Dynamic Wave

The wave setup for a given wave spectrum was re-evaluated with the radiation stress term including the low-frequency terms. This setup which is referred to here as "dynamic wave setup", was compared with the steady setup, which is generated by including only the non-periodic radiation stress terms. The results of the study showed that the dynamic wave setup is greater than the steady wave setup, sometimes almost double its value. Therefore, the dynamic wave setup is important for engineering applications, particularly in the study of storm surges and coastal engineering problems.

scholarly journals Temporal variation in fish assemblage composition on a tidal flat

2004 ◽  
Vol 52 (1) ◽  
pp. 47-58 ◽  
Author(s):  
Henry L. Spach ◽  
Rodrigo S. Godefroid ◽  
César Santos ◽  
Roberto Schwarz Jr. ◽  
Guilherme M. L. de Queiroz
Keyword(s):  
Tidal Flat ◽  
Fish Assemblage ◽  
Annual Variation ◽  
Full Moon ◽  
Temporal Change ◽  
High Tide ◽  
Great Influence ◽  
Assemblage Composition ◽  
Combined Action ◽  
Wind Intensity

Annual variation in the fish assemblage characteristics on a tidal flat was studied in coastal Paraná, in southern Brazil. Fish were collected between August 1998 and July 1999, during the diurnal high tide and diurnal and nocturnal low tide of the syzygial (full moon) and quadrature (waning moon) tides, to characterize temporal change in assemblage composition. A total of 64,265 fish in 133 species were collected. The average number of species and individuals, biomass, species richness, diversity (mass) and equitability varied significantly over time . The dissimilarity of the assemblage was greatest in August, September and October in contrast with the period from November to January, with the lowest dissimilarity. The combined action of water temperature, salinity and wind intensity had a great influence over the structure of the fish assemblage.

scholarly journals Erosion problems of shore line and counter measurement by various geomaterials

2019 ◽  
Vol 265 ◽  
pp. 01010
Author(s):  
Eun Chul Shin ◽  
Sung Hwan Kim ◽  
Abdul Hakam ◽  
Bambang Istijono
Keyword(s):  
High Tide ◽  
Storm Surges ◽  
Coastal Zones ◽  
Coastal Structures ◽  
Economic Activities ◽  
Natural Rock ◽  
Sea Sand ◽  
Coastal Beach ◽  
Materials Used ◽  
Erosion Protection

Coastal regions are vulnerable to erosion and depletion of land areas for human habitation and economic activities. A description of various types of the hydraulic structures associated in erosion protection applications are provided. Recently, because of the shortage of natural rock, traditional forms of river and coastal structures have become very expensive to build and maintain. Therefore, the materials used in hydraulic and coastal structures are changing from the traditional rubble and concrete systems to the cheaper materials and systems. Erosion problems in coastal zones are become increasingly serious due to the development of artificial activities related to the expansion of city functions, industrial complexes and harbour facilities, as well as the removal of sea sand for use in aggregate resources at the construction sites, which is a major factor in the inflow and outflow of sea sand. In addition, the environmental and economical importance of the coastal beach zones is increased. However, coastal beach zones are constantly eroded by waves accompanied with the rising water level due to storm surges, hurricanes, winter storm impact, and high tide. This erosion motion accelerates the regression of the coastal cliff due to the regression of the dunes or the shoreline. In addition, the regression leads to loss of real estate in the hinterland and ruins the shock-absorbing zone between land and sea. The application benefits for erosion protection are discussed. Several case studies are included.

The Study of the Impact for Coastal Engineering on High Water Level Induced by Storm Surges in Bohai Bay

2011 ◽  
Vol 94-96 ◽  
pp. 810-814
Author(s):  
Jin Shan Zhang ◽  
Wei Sheng Zhang ◽  
Chen Cheng ◽  
Lin Yun Sun
Keyword(s):  
Water Level ◽  
Storm Surge ◽  
Large Scale ◽  
Storm Surges ◽  
High Water ◽  
Coastal Engineering ◽  
Cold Wave ◽  
Bohai Bay ◽  
Ocean Engineering ◽  
The Impact

Bohai Bay is an semi-closed bay, the storm surge disaster is very serious in past. Now more and more large ocean engineering are built here, To study changes of storm surge induced by the construction of large-scale coastal engineering in Bohai Bay in present, 2D numerical storm surge model is established with large - medium - small model nested approach. The three most typical storms surges: 9216, 9711 and by cold wave in October 2003 are simulated in the condition of before and after implementation of planning projects in Bohai Bay. Changes of storm surge water level due to implementation of artificial projects are analysis in this paper.

Drivers of nano- and microplanktonic community structure in a Patagonian tidal flat ecosystem

2019 ◽  
Vol 41 (5) ◽  
pp. 621-639
Author(s):  
Juan F Saad ◽  
Maite A Narvarte ◽  
Mariza A Abrameto ◽  
Viviana A Alder
Keyword(s):  
Tidal Flat ◽  
Tidal Flats ◽  
Size Spectrum ◽  
Spatial Gradient ◽  
Total Biomass ◽  
Total Density ◽  
Phytoplankton Structure ◽  
Tidal Transport ◽  
Sw Atlantic ◽  
Inshore Waters

ABSTRACT Tidal flats are exceptionally dynamic coastal ecosystems. Tides are their main source of energy, whose influence decreases landwards (as land elevation increases), thus shaping physical, chemical and biological gradients. In this study, we assess whether the structure of nano- and microplankton varies along a spatial gradient in San Antonio Bay (SAB, SW Atlantic), a semi-desert coastal ecosystem with a wide tidal flat and a macrotidal regime. We hypothesize that the tidal effect shapes SAB’s both taxonomical groups and size spectrum. The seasonal sampling of 9 sites revealed that diatoms and small flagellates were the most abundant groups, together accounting for over 75% of total density in practically all sites and seasons. High densities of meroplanktonic stages of Ulva lactuca were recorded in spring at the innermost sites, accounting for over 95% of all planktonic cells. Slopes of the size spectrum analysis were in line with highly productive inshore waters (mean, −0.64) and showed that larger phytoplankton was the main contributor to total biomass, despite its decreasing importance toward inner sites. The spatial and seasonal variations found for lower trophic web compartments provide evidence of the importance of tidal transport in ruling phytoplankton structure in tidal flats under strong macrotidal regimes.

scholarly journals High-Tide Floods and Storm Surges During Atmospheric Rivers on the US West Coast

2021 ◽  
Author(s):  
Christopher G Piecuch ◽  
Sloan Coats ◽  
Sönke Dangendorf ◽  
Felix W Landerer ◽  
J T Reager ◽  
...  
Keyword(s):  
West Coast ◽  
High Tide ◽  
Storm Surges ◽  
Atmospheric Rivers ◽  
The Us ◽  
Us West

scholarly journals Shoreward Sand Transport after Offshore Sand Capping on Nakatsu Tidal Flat

2010 ◽  
Vol 66 (1) ◽  
pp. 1181-1185
Author(s):  
Yukiko ASHIKAGA ◽  
Satoquo SEINO ◽  
Takaaki UDA ◽  
Yoshihiko AZETSU ◽  
Akihisa AYAME ◽  
...  
Keyword(s):  
Tidal Flat ◽  
Sand Transport
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