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Velegrakis A. F. Trygonis V. Chatzipavlis A. E. Karambas Th. Vousdoukas M. I. Ghionis G. Monioudi I. N. Hasiotis Th. Andreadis O. Psarros F. 《Natural Hazards》2016,83(1):201-222
This contribution presents the results of a study on the shoreline variability of a natural perched urban beach (Ammoudara, N. Crete, Greece). Shoreline variability was monitored in high spatio-temporal resolution using time series of coastal video images and a novel, fully automated 2-D shoreline detection algorithm. Ten-month video monitoring showed that cross-shore shoreline change was, in some areas, up to 8 m with adjacent sections of the shoreline showing contrasting patterns of beach loss or gain. Variability increased in spring/early summer and stabilized until the end of the summer when partial beach recovery commenced. Correlation of the patterns of beach change with wave forcing (as recorded at an offshore wave buoy) is not straightforward; the only discernible association was that particularly energetic waves from the northern sector can trigger changes in the patterns of shoreline variability and that increased variability might be sustained by increases in offshore wave steepness. It was also found that the fronting beachrock reef exerts significant geological control on beach hydrodynamics. Hydrodynamic modelling and observations during an energetic event showed that the reef can filter wave energy in a highly differential manner, depending on its local architecture. In some areas, the reef allows only low-energy waves to impinge on the shoreline, whereas elsewhere penetration of higher waves is facilitated by the low elevation and limited width of the reef or by the presence of an inlet. Wave/reef interaction can also generate complex circulation patterns, including rip currents that appeared to be also constrained by the reef architecture. 相似文献
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S. E. Poulos K. Gaki-Papanastasiou P. Gialouris G. Ghionis H. Maroukian 《Environmental Earth Sciences》2012,66(3):955-966
The present investigation concerns the formation and evolution of the dune field of the central part of the Kyparissiakos Gulf (western coast of Peloponnesos, Greece). This dune field is associated with the Kaiafas lagoon and consists of four dune lines that lie at distances of 600, 200, 100 and 70 m from the coastline. The dune field has developed on top of a barrier beach that formed subsequently to the completion of the last phase of rapid sea level rise, i.e. after 6,000 BP, consisting mostly of medium sand with good sorting, due to its aeolian formation. Assuming a steady wind regime and adequate sediment availability during the late Holocene, a period of approximately 1,350 years has been estimated to be the minimum time required for the formation of the dune field; this formation period may also include intervals when the development processes were more or less intensive. On the basis of radio-carbon dating, secondary fluctuations of air temperature and published information, it is proposed that the 4th (oldest) dune line started forming between the years 400 AD and 1,000 AD, whilst the 1st (youngest) dune line started forming after 1,520 AD. The dune field, especially its youngest line seems to be in equilibrium with its adjacent beach zone and the nearshore hydrodynamics, being beyond the reach of wave run-up. On the other hand, the dune field, over the past decades, has been subjected to intense human intervention (agriculture, construction, forest fires, etc.) that has locally destroyed and/or destabilised part of the dunes. Finally, the expected sea level rise, due to global warming, is undoubtedly a threat to the existence of the dune field. 相似文献
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