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

Mission géoarchéologique

Chabrol Antoine, Kapsimalis Vasilios, Stephan Pierre, Virmoux Clément. Mission géoarchéologique. In: Bulletin de correspondance hellénique. Volume 138, livraison 2, 2014. pp. 694-703

Simulation of the Nearshore Sediment Transport Pattern and Beach Morphodynamics in the Semi-Enclosed Bay of Myrtos, Cephalonia Island, Ionian Sea

Myrtos Beach (Cephalonia Island, Ionian Sea, Greece) represents a pocket beach with strong touristic, economic and natural interest. In this research, the morphodynamic behavior of the coastal area (e.g., hydrodynamic and sedimentary state, morphology, orientation, etc.), the current wave conditions (extreme and dominant waves, wave exposure), and also external factors, such as human impact and the geotechnical condition of the wider area, are examined. Short- and medium-to-long-term analysis took place, such as mapping, sediment analysis, wave/wind analysis, numerical modeling, and satellite monitoring, in order to identify the dynamic forcing parameters related to geomorphology, sedimentology, and hydrology that prevail in the area. Additionally, the intense tectonics, the karstified limestones, and the steep slopes of the cliffs in combination with the frequent seismic events on the island set up a geotechnically unstable area, which often cause landslides on the beach of Myrtos; these supply the beach with a large amount of aggregates, constituting the main sediment supply. Wave exposure forcing conditions, longshore–rip current direction, and other hydrodynamic processes are stable with high values in the area, causing notable sediment transport within the bay boundaries. As a result, at Myrtos Bay there is a dynamic balance of the natural system, which is directly affected by human interventions. Taking also into consideration that Myrtos is one of the most famous beaches in Greece and one of the main attractions of Cephalonia Island with thousands of visitors every year, beach management must be focused on preserving the natural system of the coastal area

Coastal Vulnerability Assessment for Future Sea Level Rise and a Comparative Study of Two Pocket Beaches in Seasonal Scale, Ios Island, Cyclades, Greece

The coastal zone may be considered as the location where the marine and land environments interact dynamically and coexist with human societies. Globally, natural and human systems are being severely threatened by the sea level rise related to climate change. The outcome between the dynamic relationship of coastal environments and marine processes, and the future sea level rise as predicted by scientific reports, is the vulnerability of coastal areas such as sandy beaches, pocket beaches and low-lying coastal areas. The current research aims to assess the coastal vulnerability of Ios Island, Cyclades, Greece for the next 100 years and to identify areas that are comparatively more vulnerable to future sea level changes. Moreover, the seasonal changes concerning sedimentological and morphological characteristics of two pocket beaches of Ios Island, Mylopotas and Magganari, are also examined. From the application of the Coastal Vulnerability Index, 92.37% of the total length of the coastline of Ios Island is characterized by a very low vulnerability as it consists of rocky shores and cliffs, while sandy and pocket beaches are characterized by a very high vulnerability. From the fieldworks and data processing, the seasonal changes mainly concern the seabed’s topography, the sediments’ texture of the collected sand samples, the foreshore and backshore topography, as well as seasonal shoreline displacement, using the Digital Shoreline Analysis System tool (DSAS)

Coastal Vulnerability Assessment for Future Sea Level Rise and a Comparative Study of Two Pocket Beaches in Seasonal Scale, Ios Island, Cyclades, Greece

The coastal zone may be considered as the location where the marine and land environments interact dynamically and coexist with human societies. Globally, natural and human systems are being severely threatened by the sea level rise related to climate change. The outcome between the dynamic relationship of coastal environments and marine processes, and the future sea level rise as predicted by scientific reports, is the vulnerability of coastal areas such as sandy beaches, pocket beaches and low-lying coastal areas. The current research aims to assess the coastal vulnerability of Ios Island, Cyclades, Greece for the next 100 years and to identify areas that are comparatively more vulnerable to future sea level changes. Moreover, the seasonal changes concerning sedimentological and morphological characteristics of two pocket beaches of Ios Island, Mylopotas and Magganari, are also examined. From the application of the Coastal Vulnerability Index, 92.37% of the total length of the coastline of Ios Island is characterized by a very low vulnerability as it consists of rocky shores and cliffs, while sandy and pocket beaches are characterized by a very high vulnerability. From the fieldworks and data processing, the seasonal changes mainly concern the seabed’s topography, the sediments’ texture of the collected sand samples, the foreshore and backshore topography, as well as seasonal shoreline displacement, using the Digital Shoreline Analysis System tool (DSAS)

Assessment of Wave Storm-Induced Flood Vulnerability in Rhodes Island, Greece

Coastal areas are threatened by extreme meteorological phenomena, such as wave storms. Therefore, the analysis of such events, such as providing information for their potential hazards assessment, is a key element in coastal management. In this study, a preliminary assessment of flood vulnerability due to storms was performed in Rhodes Island, Greece. Firstly, storm events were defined in terms of significant wave height, peak period, and duration, and they were grouped by means of cluster analysis into five classes (from weak to extreme) reflecting the intensity of each event. Subsequently, flood hazard was assessed by using an empirical formula for wave run-up calculations on cross-shore profiles and storm surge data at the region. Finally, a Flood Vulnerability Index (FVI) was used for assessing vulnerability according to a scale from very low to very high. The most intense storms were found to occur in the eastern, southeastern, and southern part of the island. More than 60% of storms were classified as weak, while extreme events were found to occur with a frequency of less than 2.5%. Regarding flood hazard and vulnerability, the maximum values of wave run-up were calculated in the southeastern region, but the most vulnerable part was found to be the northwestern region, as the FVI was assessed as very high for weak and extreme events

Prediction of Soil Loss in a Reservoir Watershed Using an Erosion Model and Modern Technological Tools: A Case Study of Marathon Lake, Attica in Greece

Marathon Lake is an artificial reservoir with great environmental, ecological, social, and economic significance because it was the main source of water for Athens, the capital of Greece, for many years. The present study details the first attempt to map sedimentation in Marathon Lake in detail, using bathymetric mapping and soil erosion field surveying of the torrent watershed areas. First, the results of a bathymetric survey carried out in 2011 were compared with topographic maps that pre-date the construction of the dam. Based on this comparison, an estimated 8.34 hm3 of sediment have been deposited in the 80 years since the dam’s construction. In the current survey, the Revised Universal Soil Loss Equation (RUSLE) was used to estimate soil loss in the watershed area of the streams that end in Marathon Lake. The estimated value from the RUSLE was substantially lower (3.02 hm3) than that calculated in the bathymetric survey

Long-Term Shoreline Displacements and Coastal Morphodynamic Pattern of North Rhodes Island, Greece

Shoreline evolution and seabed morphology changes depend on coastal geomorphology as well as hydrodynamics of the nearshore region. Τhis study investigates the morphological evolution of the northernmost headland of Rhodes Island, Greece, using a method that combines historical shoreline evolution analysis and numerical modelling of coastal processes. The satellite and aerial imagery analysis under a GIS platform reveals that, since 1982, the overall surface area of the backshore has slightly increased, though in shorter period times, large variations have been identified. The part of the beach that is most prone to extreme changes is the spit-like formation at the tip of the headland. Wind-generated waves and induced currents are the main forcing factors that affect the shape and orientation of the spit-like beach. This spit-like morphology changes seasonally due to variations in the dominant wave regime. West sector waves cause sediment deposition at the eastern sector of the spit-like formation, whereas strong southeast wave events during the winter favor accretion at the west sector, inducing an asymmetrical shape. Thus, the analysis results indicate an annual balance in sediment transport