A geomorphological investigation of the formation and evolution of the Kaiafas sand-dune field (Kyparissiakos Gulf, Ionian Sea,eastern Mediterranean) in the Late Holocene

摘要

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.