Impact of sea-ports constructions on dynamics of connected natural shores within untidal seas

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Назва тому
Natural conditions of building and exploitation, sea-ports and port constructions are different for tidal and untidal seas. Principal differences are as follows: in the coastal zone of untidal seas, there are no essential tidal sea-level fluctuations including those of large amplitude and there are no reversible tidal currents. Tidal flats and muddy alongshore flows of drifts occur seldom. Differences of tidal characteristics influence the choice of construction and the nature of port configurations. An acute deficiency of drifts in the coastal zone poses the greatest danger for connected shores after the completion of port-related constructions (e.g., jetting, canals, piers). For untidal systems (amplitudes less than 0.5 m), ports can be divided according to environmental conditions into those which are situated: a) in harbours with shallow nearshore water depths, b) in harbours with deep nearshore water depths, c) in lagoons and limans, d) in river estuaries, e) on smoothed deep nearshore bottoms, and f) on smoothed shallow nearshore bottoms. Different combinations of the variants mentioned above are possible. Ports from a, c and f deserve the greatest attention. Ports developed in these environments require numerous and expensive construction and offer the greatest potential impact on connected shores. In this work conditions ofa, c and f types of environments are analyzed. Under such conditions outer portal constructions (piers, jetties, navigable canals, moles, etc.) represent artificial obstacles for sediment drift movement. These structures promote redistribution of drifts in the coastal zone and alter conditions of development of connected natural shores.
Ключові слова
sea-ports, untidal seas, exploitation, constructions
Бібліографічний опис
"Proceedings of International Symposium on Exploitation and Management Island Coast and Embayment Resources ( Haikou City and Sanya City,Nov 1-10, 1990), Hainan Province, China