Publications by Year: 2019

2019
Evelpidou N, Gatou M-A, Karkani A. Coastal rehabilitation: general strategies and examples. In: et al. Merino A Best practices on land degradation and restoration in Mediterranean environments. Ibader, Universidade de Santiago de Compostela, Lugo; 2019. pp. 129-140.
Petropoulos A, Kapsimalis V, Evelpidou N, Anagnostou C. Geomorphological and sedimentological dynamic processes at the semi-closed Bay Platis Gialos (Sifnos Island). 15th International Congress of the Geological Society of Greece. 2019.Abstract
Platis Gialos Bay located at the Southern part of Sifnos Isl. and his length is determined at 1.000 m, with SE direction. The coast of Platis Gialos Sifnos has been under erosion and permanent coastal retreat for several years, especially at the central and west part of the beach. The main causes of coastal erosion are anthropogenic.This paper focuses most intently on the geomorphological and sedimentological dynamic processes of the Bay which forming the current situation. For this reason a number of tasks took place in order to determine the level of disturbances of this dynamic equilibrium. This study included two phases of survey for two different periods (summer/winter). The first phase deals with the geomorphological and sedimentological coast characteristics, and includes: i) long-term geomorphological evolution of the coastal zone through the analysis of satellite images (Google Earth), in order to estimate the intensity of coastal erosion. ii) topographic sections at the surface of the coastal zone, through D-GPS (Spectra Precision SP80 GNSS Receiver), perpendicular to the coastline, iii) sediment sampling in the subaerial coastal area, iv) analytical recording and mapping of the summer and winter shorelines via the D-GPS, v) the situation of the potential feeders of the shore with materials, necessary for the formation of an alluvial beach, and vi) recording of land uses (Fig.1). The second phase, includes the geomorphological and sedimentological characteristics of the marine area, in particular: i) topographic sections of the bottom surface until the depth of 1.5 m, through D-GPS, perpendicular to the coastline ii)sediment sampling in the subaquatic marine area, iii) data of the numerical recomposition of the wind and wave conditions of the study area, iv) bathymetric eco-sonar data (Lowrance LCX-15MT), v) side-scan single beam eco-sounder (StarFish 450), to determine the seabed morphological features of the bay and, vi) substrate component mapping (Fig. 1). Laboratory analyzes were followed by the methods of dry granulometry, in order to categorize it, in different types on the basis of Folk & Ward (1957) method through GRATISTAT (v.8) software.
Polidorou M, Saitis G, Evelpidou N. Beachrock development as an indicator of palaeogeographic evolution, case of Akrotiri Peninsula, Cyprus. 15th International Congress of the Geological Society of Greece. 2019.Abstract
Akrotiri Penisnsula is located west of Limassol at the Southern end of the Island of Cyprus. It covers an area of approximately 100km². The development of the peninsula started with the deposition of calcareous marls in to the Episkopi grabben during the Miocene which resulted the Akrotiri High in the form of an isolated island. The maritime space between the Akrotiri Island and the mainland eventually closed during the Quaternary and several geomorphic features were developed. Beachrocks identified at three continuous pocket beaches at the southwest part of the Akrotiri peninsula. Detailed GNSS measurements and GIS analysis revealed that the area is uplifted. A direct relationship between the development of the beachrocks and the paleogeographic evolution of the area is apparent. Additionally, results from Petrographic, mineral and sedimentary analysis on beachrock samples are indicating a continuous supply of material from the nearby Kouris River. A gradual reduction of the sediment granulometry consists the beachrock is observed. Also the transition of the texture of the samples from non-uniform to uniform is observed. The sample mineralogy varies eg quartz, alkaline feldspars, carbonate minerals, ortho and clino pyroxenes, serpentinites, hornblende, muscovite. A reduction in the contribution of overbearing minerals (according to their hardness) was observed from North to Southern beachrock slabs and the increase of carbonates, quartz and feldspart. It should be noted that there is a strong participation of fossils fragments were a number of them was preserved in good condition. SEM-EDX analysis were conducted and showed that the micritic and sparitic crystals of cement are consisted by High Magnesium Calcite +(>4 mol% CaCO3 or 1.2 wt.). The cement agent forms an isopachous coating around the sediment grains and with meniscus forms connect all the sedimentary particles which leads to the formation of a high density beachrock slabs.
Al Imran M, Nakashima K, Evelpidou N, Kawasaki S. Factors affecting the usease activity of native ureolytic bacteria isolated from coastal areas. Geomechanics and Engineering. 2019;17(5):421-427.Abstract
Coastal erosion is becoming a significant problem in Greece, Bangladesh, and globally. For the prevention and minimization of damage from coastal erosion, combinations of various structures have been used conventionally. However, most of these methods are expensive. Therefore, creating artificial beachrock using local ureolytic bacteria and the MICP (Microbially Induced Carbonate Precipitation) method can be an alternative for coastal erosion protection, as it is a sustainable and eco-friendly biological ground improvement technique. Most research on MICP has been confined to land ureolytic bacteria and limited attention has been paid to coastal ureolytic bacteria for the measurement of urease activity. Subsequently, their various environmental effects have not been investigated. Therefore, for the successful application of MICP to coastal erosion protection, the type of bacteria, bacterial cell concentration, reaction temperature, cell culture duration, carbonate precipitation trend, pH of the media that controls the activity of the urease enzyme, etc., are evaluated. In this study, the effects of temperature, pH, and culture duration, as well as the trend in carbonate precipitation of coastal ureolytic bacteria isolated from two coastal regions in Greece and Bangladesh, were evaluated. The results showed that urease activity of coastal ureolytic bacteria species relies on some environmental parameters that are very important for successful sand solidification. In future, we aim to apply these findings towards the creation of artificial beachrock in combination with a geotextile tube for coastal erosion protection in Mediterranean countries, Bangladesh, and globally, for bio-mediated soil improvement.
Polidorou M, Evelpidou N, DRINIA H, Tsourou T, Salomon F, Blue L. Palaeogeography and geomorphological evolution of Akrotiri Salt Lake, Lemesos, Cyprus. RCG2019 “Geomorphology of Climatically and Tectonically Sensitive Areas”. 2019.Abstract
Akrotiri Salt Lake is located 5km west of the city of Lemesos, in the southern-most part of the island of Cyprus. The palaeogeographic evolution of the Akrotiri Salt Lake presents a great scientific interest, especially during the Holocene where the eustatic movements combined with local active tectonics and climate changes have developed a unique geomorphological environment. The Salt Lake, today a closed lagoon, which is depicted in Venetian maps (Bordon AD 1528) as being connected to the sea, can provide evidence of the geological settings and landscape evolution of the area. In this study, we investigate the development of Akrotiri Salt Lake through a series of cores which penetrated the Holocene sediment sequence. Sedimentological, micropaleontological (benthic foraminifera and ostracods) analyses and geochronological studies performed on deposited sediments, identifying the complexity of the evolution of the Salt Lake and the progressive change of the area from maritime space to an open bay and finally to a closed Salt Lake.
Polidorou M, Evelpidou N. Age evolution and geomorhic development of Akrotiri promontory sand dunes, Cyprus. RCG2019 “Geomorphology of Climatically and Tectonically Sensitive Areas”. 2019.Abstract
Two well-developed quaternary sand dune fields have been identified on the western and eastern side of Akrotiri promontory (Lemesos, Cyprus). The fields extend immediately from the low level of their source beaches onto higher ground (> 38m amsl). Geomorphic observation supported by OSL dating of multimineral sand horizons demonstrate several phases of sand accumulation in the western field in contrast to the smaller eastern system, where the evidence direct to a relatively recent dune emplacement. The effects of climatic change, relative sea-level change and anthropogenic influence in dune evolution, have been evaluated in both sites in combination with documented evidence of human induced destabilization of the western sand dune field during the 1970s and 1980s. Both fields share similar topographic settings and situated in close proximity but they do not share an entirely similar evolution history. The  οbservations and the data suggest the combination of local and regional control of the development of the sand dunes and the geochronological analysis with luminescence methodology support the ability of the method to reconstruct the evolution of sand dunes fields in the eastern Mediterranean area.
Giannikopoulou K, Evelpidou N, Harris S, Poulos S. Seafloor structure of Argostoli Bay. RCG2019 “Geomorphology of Climatically and Tectonically Sensitive Areas”. 2019.Abstract
In order to investigate the formation processes of the seafloor of Argostoli bay (Cephalonia Island, Ionian Sea), an extended geological survey was conducted to gather details about the near-surface geological framework. Methods used for the survey include high resolution subbottom seismic profiles (29.4 line kilometers; EdgetechCHIRP system at frequencies 2-16 kHz) side-scan sonar backscatter surveys of the seafloor (approximately 67 line-km, Starfish 450F), single-beam bathymetry (approx. 67 line-km, Lowrance LCX-15MT Sonar system), and bottom sampling including bottom sediment grab samples (van veen grab sampler) and short sediment cores. The survey was focused at both ends of Argostoli Bay (i.e., Argostoli and Livadi inlets). Preliminary analysis of the sub-bottom profiles in the upper 12-20 m reveals a clear pattern of sediment layers, in both ends of the bay. The uppermost layers been deposited horizontally with small differences in their orientation in the area of Argostoli inlet, while the presence of gas is more pronounced in Livadi inlet. Moreover, in Argostoli inlet a palaeo-surface is visible (probably the base of Holocene sedimentary cover) with minor channel features, likely indicating a shallow river valley. Side- scan mapping in combination with sediment samples and cores showed that the surface sediment consists mostly of finegained material, rich in organic matter over a gravel-lag deposit that may represent the transgressive surface in the area.
Saitis G, Polidorou M, Evelpidou N. Beachrock formation mechanism through minerochemical analysis and cement characteristics. Case study W. Akrotiri Peninsula, Cyprus. RCG2019 “Geomorphology of Climatically and Tectonically Sensitive Areas”. 2019.Abstract
Beachrocks are hard coastal sedimentary formations consisted from various beach sediments, coastal fauna residues and anthropogenic articles. Beachrocks are rapidly cemented through precipitation of carbonate cements typically consisted of High-Magnesian Calcite (HMC), which commonly precipitates in shallow marine environments, (>4 mol % CaCO3 or 1.2 wt. %) or aragonite (Ar). However, debate still exists concerning the accurate depositional environment of beachrocks and data for the mechanism of their formation are considered necessary. This study aims to contribute to the understanding of the beachrock formation, using mineralogical and geochemical methods, analyzing the cement and the consolidated sediments. Bulk samples were collected from three consecutive beaches located at the West part of Akrotiri Peninsula (Cyprus island). The samples were examined under polarizing microscope for the determination of the cement (HMC as micritic and sparitic crystals), its characteristics (isopachous bladed coating, formation of meniscus etc) and the participation of well-preserved fossil fragments. The mineralogical analysis, with the use of XRD analyzer, indicated a variety of minerals which consisting the beachrock (quartz, carbonates, plagioclase, olivine, biotite, zircon etc). Using SEM-EDS it was possible to accurately determine the cement composition and to observe its crystal characteristics. The cement agent was mainly consisted by High-Magnesian Calcite (HMC) of different crystal sizes and matrix material was present as secondary pores filling. The three studied beachrocks at the west of Akrotiri peninsula, were formed in the middle-low intertidal zone. Evidence of continuous uplift of the beachrock is observed both from geomorphological analysis and through its infrastructure. The beachrocks were highly affected by the nearby Kouris river, which supplied the material derived from the inner Cyprus areas rich in Mg2+ rocks (eg. ophiolites) and Ca2+ (eg. limestones, marbles).
Komi A, Petropoulos A, Evelpidou N, Poulos S, Kapsimalis V. A comparative study of seasonal changes of the sedimentological and geomorphological characteristics of Mylopotas and Manganari Beach in Ios Island, Cyclades (Greece). RCG2019 “Geomorphology of Climatically and Tectonically Sensitive Areas”. 2019.Abstract
Sedimentological and geomorphological features of Mylopotas and Manganari beaches in Ios Island are investigated in order to determine seasonal changes in the texture of coastal sediments and shoreline position caused by both natural processes and human activities. The fieldwork was conducted in April 2018 and September 2018 including mapping of beach morphology in seasonal scale through topographic monitoring of shoreline, coastline and fixed cross sections in the sites under investigation using a differential GPS. In addition, sediment sampling was carried out along selected cross sections in beaches of Mylopotas (three) and Manganari (two). Grain size analysis and statistical processing were realized to reveal spatial and temporal changes of sediment parameters, such as sorting, skewness, mean and kurtosis. The results indicate a rather homogenous grain size distribution at each study area, with the majority of samples being classified as slightly gravelly sand. DGPS measurements of shoreline position in Manganari Beach indicate changes that vary between 2.50 m and 4.70 m, with the maximum displacement to be observed in the southern part of the beach, where the shoreline is retreated during spring period. Seasonal variations of shoreline position in Mylopotas Beach are up to 4.50 m with the shoreline to be advanced during spring period in the southern and northern part of the beach, while the minimum changes are measured in the central part, where a beachrock formation occurs. Occasional human interferences, such as small-scale beach restoration and nourishment projects, installation of leisure facilities and reshaping of sand dunes, conducted mainly during spring period, alter the coastal sediment budget and transport reinforcing shoreline retreat.
Evelpidou N, Synolakis C, Zerefos C, Repapis C, Karkani A, Polidorou M, Saitis G. Boulder deposits on the southeastern coast of Cyprus and their relation with palaeotsunami events of the Eastern Mediterranean. RCG2019 “Geomorphology of Climatically and Tectonically Sensitive Areas”. 2019.Abstract
Cyprus has a long record of tsunami waves, as noted by archaeological and geological records. Large boulder deposits have been noted in southeastern and western part of the Island. In the area of Cape Greco (southeastern Cyprus) large boulders have been noted, however, no detailed geomorphological research exists so far and the related high energy event remains undated. In this context, we focused at Cape Greco Peninsula at the southeastern coast of Cyprus, in order to record in detail large boulders deposits. The accumulation of the boulders along the uplifted coastline (3m amsl) was recorded. The boulders are fragments of a layer of an upper Pleistocene aeolianite, which is overlaying unconformly a lower Pleistocene calcarenite. Dimensions and spatial distribution of 272 small, medium and large boulders were documented. The precise distance of the boulders deposition from the coastline was recorded by field measurements and remote sensing with the use of GNSS, Drone mapping and GIS technics. Several large boulders weighting more than ~30 metric tons were located up to 60m inland. Geomorphologic mapping and morphometric measurements, along with the presence of marine organisms suggests that some of the boulders were removed from their original intertidal zone and were transported inland by the force of large waves. Samples of Vermetus sp. were collected from the displaced boulders in order to date the extreme event. In this work, we report and compare preliminary results from the application of widely accepted hydrodynamic equations, in order to determine the extreme event that caused their transport inland. We further attempt a correlation of the event with already known tsunami events from Eastern Mediterranean, based on the estimated wave heights and the radiocarbon dating of marine gastropods (Vermetus sp.).
Saitis G, Koutsopoulou E, Evelpidou N, Kawasaki S. A comparative study of beachrock mechanism formation focusing on natural and artificial beachrocks: case of Diolkos, Corinth, Greece and Sumuide, Okinawa, Japan. RCG2019 “Geomorphology of Climatically and Tectonically Sensitive Areas”. 2019.Abstract
Beachrocks are a window in the past environmental, geological, sedimentological and geographical conditions that were dominant on the coastal zone. The minerochemical examination of cement and the sedimentological analysis are the most efficient methods for understanding the formation mechanism. However, the examination of beachrock samples have limitations and the evidence of formation mechanism are not enough. This study emphasizes on the beachrock formation mechanism through the comparison of cement characteristics, mineral chemistry and sedimentology of beachrock occurrences from different geological and geographical setting areas Diolkos, Corinth, Greece and Sumuide, Okinawa, Japan. Furthermore, in order to investigate the beachrock formation, artificial beachrock samples were created in-vitro using sand samples and ureolytic bacteria from Okinawa under accelerating conditions. Bulk samples were collected from the study areas in order to analyze their mineralogical (XRD and SEM-EDS) and chemical (XRF) composition. Microscopy studies (optical and SEM-EDS) revealed that the cement agent from Diolkos is mainly composed of High-Magnesian Calcite (HMC) in comparison to the Sumuide beachrock which is characterized by the presence of calcite and aragonite. Additionally, the analysis revealed clastic silicate and aluminosilicate minerals. The grain composition of Diolkos slab consists of quartz, plagioclase, K-feldspar with 20% bioclasts compared to the Sumuide beachrock grains that consist of calcareous residuals from the local coral reef. The artificial beachrock investigation indicated that ureolytic bacteria that reside in the Sumuide beach sediment, are capable to precipitate aragonite coating the sediment grains and filing the pores. The cementation was most active in the top part of the samples than the bottom part. This is an indicator that the beachrock formation might occur in depths were these bacteria can be found. The artificial beachrock analysis included its physicochemical parameters using UCS penetration, pH and Ca2+ measurements, X-Ray CT-scanning, petro-graphic polarized microscopy, XRD, and SEM-EDS.
Gournelos T, Evelpidou N, Kotinas V. A dynamic erosion susceptibility model using combined fuzzy sets and logistic regression. RCG2019 “Geomorphology of Climatically and Tectonically Sensitive Areas”. 2019.
Polidorou M, Evelpidou N, DRINIA H, Tsourou T, Salomon F, Blue L. Geochronology and palaeogeography of Akrotiri Salt Lake, Lemesos, Cyprus. 7th Symposium on Archaeometry of the HSA “Archaeology-Archaeometry: 30 years later”. 2019.Abstract
Akrotiri Salt Lake is located 5km west of the city of Lemesos, in the southern-most part of the island of Cyprus. The palaeogeographic evolution of the Akrotiri Salt Lake presents a great scientific interest, especially during the Holocene where the eustatic movements combined with local active tectonics and climate changes have developed a unique geomorphological environment. The Salt Lake, today a closed lagoon, which is depicted in Venetian maps (Bordon AD 1528) as being connected to the sea, can provide evidence of the geological settings and landscape evolution of the area. In this study, we investigate the development of Akrotiri Salt Lake through a series of cores which penetrated the Holocene sediment sequence. Sedimentological, micropaleontological (benthic foraminifera and ostracods) analyses and geochronological studies performed on deposited sediments, identifying the complexity of the evolution of the Salt Lake and the progressive change of the area from maritime space to an open bay and finally to a closed Salt Lake.
Al Imran M, Kimura S, Nakashima K, Evelpidou N, Kawasaki S. Feasibility study of native ureolytic bacteria for biocementation towards coastal erosion protection by MICP method. Applied Sciences. 2019;9(20):4462.Abstract
In recent years, traditional material for coastal erosion protection has become very expensive and not sustainable and eco-friendly for the long term. As an alternative countermeasure, this study focused on a sustainable biological ground improvement technique that can be utilized as an option for improving the mechanical and geotechnical engineering properties of soil by the microbially induced carbonate precipitation (MICP) technique considering native ureolytic bacteria. To protect coastal erosion, an innovative and sustainable strategy was proposed in this study by means of combing geotube and the MICP method. For a successful sand solidification, the urease activity, environmental factors, urease distribution, and calcite precipitation trend, among others, have been investigated using the isolated native strains. Our results revealed that urease activity of the identified strains denoted as G1 (Micrococcus sp.), G2 (Pseudoalteromonas sp.), and G3 (Virgibacillus sp.) relied on environment-specific parameters and, additionally, urease was not discharged in the culture solution but would discharge in and/or on the bacterial cell, and the fluid of the cells showed urease activity. Moreover, we successfully obtained solidified sand bearing UCS (Unconfined Compressive Strength) up to 1.8 MPa. We also proposed a novel sustainable approach for field implementation in a combination of geotube and MICP for coastal erosion protection that is cheaper, energy-saving, eco-friendly, and sustainable for Mediterranean countries, as well as for bio-mediated soil improvement.
Evelpidou N, Pavlopoulos K, Vouvalidis K, Syrides G, Triantaphyllou M, Karkani A, Paraschou T. Holocene palaeogeographical reconstruction and relative sea level changes in the southeastern part of Samos Island (Greece). Comptes Rendus Geoscience. 2019;351(6):451-460.Abstract
In this paper, we focus on the southeastern coastal zone of the island of Samos (east-central Aegean Sea), in order to reconstruct the evolution of coastal landscapes and the relative sea-level changes during the late Holocene. We use geomorphological mapping, sedimentological and palaeontological proxies of late Holocene coastal deposits from two lagoon environments. We further compare our results with previously published sea-level data and we show that the southeastern part of Samos was characterized by a subsidence trend at least during the late Holocene, with RSL rise rates of ∼0.8 mm/yr. Our study additionally highlights that local-scale tectonics is responsible for the evolution of the coastal zone of Samos.
Evelpidou N, Kawasaki M, Karkani A, Saitis G, Spada G, Economou G. Evolution of relative sea level in Okinawa (Japan) during Holocene. Geografia Fisica e Dinamica Quaternaria. 2019;42(1):3-16.Abstract
Sea level indicators, such as tidal notches and beachrocks, may provide valuable information for the relative sea level (RSL) changes of an area. The study area, Okinawa, belongs to the Ryukyu Islands, Japan (Pacific Ocean), forming the emerged part of an active island arc, where the Philippine Sea plate is subducting beneath the Asian continent. Evidence of emergence has been noted by various studies. Beachrocks have also been studied, however, detailed examinations of their spatial extent and cement characteristics has not been accomplished. The purpose of this study is to discuss the RSL evolution in Okinawa through the re-evaluation of reported sea level indicators, with additional observations of beachrocks and notches and RSL predictions. Our findings suggest that the majority of Okinawa beachrocks have formed in the intertidal zone. Although the vertical uncertainty of the produced SLIPs is relatively large, there is a good agreement between the different types of sea level indicators. Comparisons with RSL predictions as well as the presence of uplifted notches further suggest that Okinawa island is generally characterized by an uplift trend, which is larger in its southern part.
Gogou M, Makri E, Katsetsiadou K-N, Evelpidou N, Karkani A, Lekkas E. Tsunami hazard and sand dune protection in West Naxos Island. 6th International Civil Protection Conference - SafeCorfu 2019. 2019.Abstract
The west coast of Naxos Isl. was hit in 1956 by the Amorgos tsunami. This study aims to: a) determine the impact of a potential tsunami similar to the one that occured in 1956, based on the island's contemporary residential and tourist development, and b) explore whether the natural geomorphs (sand dunes) in the 3 study areas (Glyfada, Agios Prokopios, Chora of Naxos) can reduce the tsunami risk. Risk assessment was based on processing field data (differential GPS) and satellite images with GIS software. Furthermore, the dunes potential risk reduction has been evaluated. Results show that taller sand dunes and vegetation provides better tsunami protection to the coast of Glyfada, than the one of Agios Prokopios. Uncontrolled tourism development without any sand dunes protection measures underline their development and, consequently, increases the tsunami risk.
Kakonas A, Karymbalis E, Chalkias C, Evelpidou N. Flood hazard assessment of the Kerinitis River catchment, North Peloponnese, Greece. 15th International Congress of the Geological Society of Greece. 2019.Abstract
Floods are among the most dangerous natural hazards affecting the development of an area. In Greece, many drainage basins are relatively small with steep slopes, configured by steep streams with braided main channel morphology. These systems are usually dry, but experience extreme flash flood events of low frequency, but high magnitude. Such exceptionally high runoff may be a source of significant damage to human infrastructure. Despite the importance of these floods, the hydrological analysis of ephemeral streams in Greece has been especially difficult due to the lack of discharge gauges.The aim of this study is to present a flood hazard assessment and mapping methodology for the Kerinitis River drainage basin which is located in the North Peloponnese. Additionally, the simulation of a flash flood event along the main channel of the river caused by an extreme rainfall event, similar to the storm that took place on January 11th and 12th, 1997 above the nearby catchment of Xerias River, using a surface GIS-based runoff model was attempted. The application of this modeling led to the direct runoff hydrograph along the Kerinitis main channel at the outlet of the basin (the apex of the fan-delta). The proposed methodologies are based on the application of GIS with the integration of various data concerning the study area.
Komi A, Petropoulos A, Evelpidou N, Poulos S, Kapsimalis V. Sedimentological and geomorphological study of Vravrona Beach, East Attica. 15th International Congress of the Geological Society of Greece. 2019.Abstract
This study focuses on the sedimentological and morphological features of Vravrona Beach, East Attica, in order to determine the seasonal changes in the textural group classification of the costal sediments, as well as, changes in coastline position (Fig. 1). Additionally, Vravrona Beach has been chosen for the assessment of a potential coastal erosion, using the Coastal Vulnerability Index (CVI) through GIS technology, since several incidents of erosion have been identified during the past decades in the broader area of East Attica (Dimou et al., 2010). For the composition of the beach profile in seasonal scale, cross sections were conducted along the beach from landward to seaward until approximately 10 m from the coastline. Beach width as well as the current coastline position for each season were measured with a differential GPS (DGPS). The land use at the landward upper limits of the study area were also measured. Along selected cross sections, sediment sampling was also conducted during January 2018 for the composition of the winter profile of the study area and during September 2018 for the composition of the summer profile of the study area. Sedimentological analyses were based on grain size distribution for the analysis of unconsolidated sediments by sieving and statistical parameters such as sorting, skewness, mean and kurtosis were calculating using GRADISTAT v. 0.4 software in order to determine the sedimentological features of the study area and the transport mechanism at the time of deposition. The textural group of the samples was also determined by Folk and Ward (1957) classification. The grain size analysis of the samples, collected between the upper limit of the beach and the coastline during summer period, show that the majority of grains is described as slightly gravelly sand and gravelly sand, but during the winter period the grains are between gravely sand and sand. The samples collected from the coastline until approximately 10 m seaward are mainly described as slightly gravelly sand and sandy gravel for both sampling seasons (Fig. 2). DGPS measurements of coastline position indicate changes that varies between 4.38 m to 7.41 m with a maximum value at 8.27 m. In agreement to field observations, DGPS measurements indicate an accumulation of sediments at the northern part of the beach during the winter period, while during summer period there is an accumulation of sediments at the southern part of the beach.
Saitis G, Evelpidou N, Kawasaki S, Koutsopoulou E, Komi A. A minerochemical cement study of a beachrock slab: The case study of Peristeria, Salamis Island. 15th International Congress of the Geological Society of Greece. 2019.Abstract
Beachrocks are consolidated sedimentary formations and are composed of coastal sediments, which are cemented through the precipitation of carbonates. The lithification takes place in the intertidal zone and can include various sediments, such as sands and gravels of clastic and biogenic origin. This study deals with the cements’ mineralogical and geochemical features of a beachrock outcrop and its aim is the contribution for further understanding on the cementation process of beachrocks. (e.g. Vieira and Ros, 2007; Vousdoukas et al., 2007; Karkani et al., 2017).
Giannikopoulou K, Evelpidou N, Baziotis I, Salomidi M, Karkani A. Coastal and marine geomorphological and environmental study of St.George Bay, Western Naxos, Greece. 15th International Congress of the Geological Society of Greece. 2019.Abstract
In order to study the geomorphological and environmental characteristics of St. George bay, western Naxos, Greece (Fig.1), a series of 14 beachrock samples were collected and examined. Two transections of the bay, based on field measurements, were designed, in order to provide a deeper understanding of the beachrock development setting. Detailed recording of the beachrocks was accomplished through scuba diving, using a sonar device, measuring tapes, GPS device and Dive Computer. Special attention was given to the cement, as to extract information about the conditions of formation of the beachrocks. Thin sections from the beachrock samples were studied through petrographic microscope in order to investigate their basic characteristics and to obtain information about their basic petrographic and mineral composition. Scanning Electron Microscopy (SEM) alongside with Energy Dispersive Spetrometry (EDS) were used for elemental analysis of the beachrock samples and their cement and Raman spectroscopy was used for identification of the cement crystal structure. For better interpretation of the results, the suggested tool, by Mauz et al. (2015), for reconstructing relative sea level in the far-field was used. In order to estimate the  ecological status of the bay, a study of the macroalgae of the area was also accomplished. Macroalgae sampling of two different methods was conducted, destructive (conventional samples) and non-destructive (photographic samples). 57 conventional samples were collected throughout the beachrock reef. These samples were prepared into herbariums and were identified in the best taxonomic level possible using stereoscope and microscope. Photographic samples were taken from the southwestern and northeastern part of St. George bay, from different types of bedrock (beachrocks, granodiorite, aeolianite) for comparison reasons. The percentages of different types of surface coverage (algal, sediment coverage) were counted for each sample, using the program Adobe Photoshop CS6. Finally, a statistical analysis of the data from the photographic samples was conducted, using the program PRIMER 5, in order to have a better evaluation of the algae data. The depth and coordinates of each conventional and photographic sample were recorded. The results regarding the beach rock samples indicate that their formation took place under meteoric and marine vadose zone conditions. Certain results indicate that the development of the beachrocks took place during a sea level rise. Finally, macroalgae statistical analyses indicated that there are no significant differences between beachrocks and other rocks as substrates and the overall ecological status of St. George bay can be characterized as good, according to the Ecological Evaluation Index (EEI, Orfanidis et al., 2003).
Karkani A, Evelpidou N, Giaime M, Marriner N, Morhange C, Spada G. Late Holocene sea-level evolution of Paros Island (Cyclades, Greece). Quaternary International . 2019;500:139-146.Abstract
Different types of sea-level markers have been used in the Eastern Mediterranean in order to assess Late Quaternary coastal evolution and relative sea-level (RSL) changes. RSL reconstructions are useful for various researches, ranging from the investigation of crustal movements to the calibration of earth rheology models and ice sheet reconstructions. GIA models have often been employed to identify stableand unstable areas and deduce tectonic rates through comparisons with observational data. It is generally assumed that most Cycladic islands (Aegean Sea, Greece) are affected by a gradual subsidence, ascribed to the thinning of the local earth crust and to isostatic processes that accompanied the post-glacial rise in sea level. The absence of morphological coastal features indicative of uplift, such as marine terraces or benches, elevated beachrocks, marine notches, or raised Quaternary coastal deposits, are often interpreted as an absence of local uplift.Although Paros Island presents great interest in terms of geoarchaeology, the evolution of its shoreline and RSL changes have not been studied in detail. The Island lies in the center of the Aegean Sea, in central Cyclades. In order to elucidate the RSL changes in the area and place an improved chronological constrain for the Late Holocene, we present new RSL index points, derived from sediment cores fromParos Island in combination with published geomorphological and sedimentological data from Paros and Naxos Island. Our results are further compared with sea-level predictions from two different GIA models in an attempt to better quantify the tectonic regime of the wider study area.
Dean S, Horton B, Evelpidou N, Cahill N, Spada G, Sivan D. Can we detect centennial sea-level variation over the last three thousand years in Israeli archaeological records?. Quaternary Science Reviews. 2019;210:125-135.Abstract
Archaeological remains are valuable relative sea-level (RSL) indicators in Israel, a tectonically stable coast with minor isostatic inputs. Previous research has used archaeological indicators to argue for centennial sea-level fluctuations. Here, we place archaeological indicators in a quality-controlled dataset where all indicators have consistently calculated vertical and chronological uncertainties, and we subject the data to statistical analysis. We combine the archaeological data with bio-construction data from Dendropoma petraeum colonial vermetids. The final dataset consists of 99 relative sea-level index points and 12 limiting points from the last 4000 a. The temporal distribution of the index points is uneven; Israel has only four index points before 2000 a BP. We apply an Errors-In-Variables Integrated Gaussian Process (EIV IGP) to the index points to model the evolution of RSL. Results show RSL in Israel rose from −0.8 ± 0.5 m at ∼2750 a BP (Iron Age) to 0.0 ± 0.1 m by ∼1850 a BP (Roman period) at 0.8 mm/a, and continued rising to 0.1 ± 0.1 m until ∼1600 a BP (Byzantine Period). RSL then fell to −0.3 ± 0.1 m by 0.5 mm/a until ∼650 a BP (Late Arab period), before returning to present levels at a rate of 0.4 mm/a. The re-assessed Israeli record supports centennial-scale RSL fluctuations during the last 3000 a BP, although the magnitude of the RSL fall during the last 2000 a BP is 50% less. The new Israel RSL record demonstrates correspondence with regional climate proxies. This quality-controlled Israeli RSL dataset can serve as a reference for comparisons with other sea-level records from the Eastern Mediterranean.