The influence of the Evros River on the recent sedimentation of the inner shelf of the NE Aegean Sea

Abstract The transboundary Evros River discharges into the Alexandroupolis Gulf, located in the inner shelf of the northeastern Aegean Sea, where it has formed an extended delta. Grain-size and mineralogical analyses of five sediment cores, collected in the subaqueous delta, provide the following information about recent sedimentation processes in the northeastern part of the Aegean shelf: (a) river mouth deposits, consisting of coarse-grained sediments, are mainly deposited in front of the active mouth, whilst some sandy material is expected to be transported alongshore by nearshore currents; (b) delta front deposits are characterised by fine-grained sediments that include evidence of human activities which have taken place, in a more intense way, since the 1950s; and (c) prodelta deposits are represented by almost uniform riverine mud that cover the pre-existed relict sands of the shelf, indicating also the limit (some 15 km to the SW) of the influence of riverine sedimentation on the seabed of the inner shelf of the Alexandroupolis Gulf

Grain-Size Trend Analysis for the Determination of Non-Biogenic Sediment Transport Pathways on the Kwinte Bank (southern North Sea), in Relation to Sand Dredging

Grain size trend analysis is applied to the determination of sediment transport pathways over the Kwinte Bank southern North Sea which had been subjected to intensive dredging within the context of the environmental impact of dredging activities On the basis of the results of grain size trend analysis focused mainly upon the transportation of the non biogenic sedimentary material (<2 mm) it appears that (1) there is a main sediment pathway over the western (bank crest) and central (dredged area) part of the bank directed toward the NE whilst a secondary pathway is established over its eastern gently sloping flank h wing a SE direction Further the present analysis shows that the area of the central (dredged) depression acts more as a by passing zone rather than as a depo-centre for the non biogenic sediments Comparison undertaken with the results of an earlier investigation for a non-dredged area at the northern end of the same bank reveals that the depression due to dredging modifies significantly the sediment transport pathways this may be attributed to a change in the seabed morphology which in turn modifies the near bed hydrodynamics (related to tide and/or storm events

Sea-level rise trends in the AtticoCycladic region (Aegean Sea) during the last 500 years

Sea-level change during the last 18,000 years is a combination of eustatic, isostatic and tectonic contributions. In an effort to minimize the tectonic contributions, our study of sea-level changes in the Aegean Sea within historical times is focused on the aseismic Attico-Cycladic geotectonic zone. On the basis of archaeological information and radiocarbon dating of coastal sedimentological formations, a sea-level curve for the Attico-Cycladic massif has been constructed for the past 5000 years and compared with existing curves. According to this curve, the rapid increase of sea level concluded prior to 5.5 ka and was followed by a slow steady rise at a rate of 0.9 mm/a up to its present stage. The latter is attributed primarily to the process of thermal expansion and secondarily to the residual melting of the glaciers and existing icecaps. By extrapolation of the curve, the sea level at the end of the 20th century is predicted to be about 9 cm higher than the present level; this value is much lower than the prediction of the last IPCC report (49 cm). If higher SLR rates are realised in the next few decades, then the excess 40 cm of the IPCC prediction can be attributed to human-induced global climatic change

The role of coastal morphology in influencing sea level variations induced by meteorological forcing in microtidal waters: examples from the Island of Crete (Aegean Sea, Greece)

Sea surface variations due to strong (northerly) onshore winds are compared over three different geomorphological settings of the essentially tideless (tidal range < 10 cm) northern coast of Crete (southern Aegean Sea): (i) an open beach zone; (ii) a beach zone with the same offshore characteristics as the previous zone, but protected by a shore-parallel reef; and (iii) a pocket beach located in the cove of a semienclosed gulf. Even though the three beach zones are exposed to similar meteorological forcing (strong northerly winds with speeds > 10 m s?1), they developed different water level variations depending on the local morphological conditions. The beach zone situated in the semienclosed gulf experienced a 3.3 times larger offshore sea surface rise (10 cm) than the unprotected open beach. The presence of the reef, on the third beach, caused a 2.7 times higher increase of the nearshore sea surface elevation (i.e., up to 24.5 cm) than the nearshore sea surface rise (9 cm) measured at the nearby unprotected open coast that experiences similar offshore hydrodynamic conditions. The sea surface variations in the offshore zone are induced primarily by wind forcing and, secondarily, by barometric pressure fluctuations: their corresponding ratios vary from 3.2??1 in the unprotected open beach, to 2.2??1 in the pocket beach located in the semienclosed gulf. Sea surface rise within the nearshore zone is controlled mainly by the wave set-up, due to breaking waves; this, at the open coast, is about 1.3 times larger than the wind set-up. Finally, the presence of the reef amplifies sea surface rise along the shoreline, which can easily exceed 0.4 m (15 times the offshore sea surface rise)