The aim of this paper is to provide further information of the tafoni development. At Theologos area, Fthiotis Prefecture, north Euboean Gulf, a carbonate formation hosts a variety of well developed tafoni. 165 tafoni were, randomly, selected by means of a detailed geomorphological investigation. The presence or absence of lichen cover, rock flaking, and cavern floor debris, amalgamation, salt flakes, different kind of structures, biological communities, were noted, while measurements regarding their dimension took place. Surface hardness values, obtained using a Schmidt hammer. Although, there is no evidence of the key factor that drives the growth of tafoni, salt weathering and low strength seems determinant of their formation. Moreover, much of the evidences suggest that joints are actively influencing the origin and the morphology of tafoni. It is possible that tafoni formation is initiated at weak zones. The studied tafoni are actively developing and are not relict features inherited from a past environment. It seems that their evolutionary stage is II towards to III. The results of chemical and mineralogical analysis indicate that during the cavernous weathering, silica, sulphates, alumina and iron oxides have replaced carbonate grains. Also, at the non-weathered part of the rock, the main mineralogical phases are calcite and dolomite.

Natural hazards, on a national and international scale, have increased in the last years as a consequence of climatic changes and human activity resulting in an unfavourable impact on socio-economic conditions. Catastrophic phenomena related to river floods as well as, from erosional and meteorological events, and human intervention. The Vulnerability being particularly high in the regions intensely populated, like the analyzed case study, high is the Risk. The importance of geomorphological studies in assessing natural hazards due to river floods was brought into focus with recent floods event that occurred in urban areas in NW Peloponnesus, Greece. During the autumn and winter months intense rainfalls persisted for several hours producing severe flash flood mainly in the alluvial playing of same urban streams - river. There were some loss of life and damage to buildings, transport infrastructure and agricultural crops. The damages are mainly due to absence of good alluvial playing management practices in recent decades, concretely after the year 1960 during the urban growth of towns. The most commonly visible consequences of the land-use change are flash floods observed in urban areas after high precipitation events. As important as the value of runoff formed from the watershed, is the process of reconstruction of the shape of the runoff hydrograph, especially the estimation of the time and value of the peak flow.

This study focuses on the estimation and management of flood risk in the drainage basin of Paratrechos or Peritsi stream in Naxos Island, through the study of geomorphological characteristics, geology, land use and topography. The catchment area of Paratrechos or Peritsi stream is approximately 54 km. High morphological relief characterizes the mountainous areas and lowland areas present mild relief. The average elevation reaches 245 m, while the average slope of the basin is 21%. The stream is known to have caused severe problems following intense rainfall, with landslides in the mountainous areas and subsidence in large parts of the road network, and with intense flooding events in the wider area of Chora of Naxos. Several floods have been recorded for Paratrechos or Peritsi stream, with the most recent at the end of March 1998, beginning of January 1999 and 18th February 2003. The aim of this study is the investigation of the relationship rain-runoff through Unitary Hydrographs, in order to estimate and evaluate the flood potential of the hydrologic basin. In order to obtain accurate results, the hydrologic basin was divided into sub-basins, based on the class of each stream, and the characteristics of each sub-basin were studied. For the optimum application of the Clark method, the data were enriched with field measurements, through the installation of a water level recorder and a meteorological station. The results from the field measurements were used to confirm the results of the method. Through this method, the maximum flow at the mouth of each sub-basin and the concentration time were calculated. Maps of flood risk were developed, with the use of ArcGis 9.3 software, presenting the characteristics of the flood risk locations in the study area. Furthermore, Instantaneous Unitary Hydrographs were produced for each sub-basin, in order to study and compare the relationship of rain-runoff and determine the causes of the risk. The identification of these areas and the application of the method were accomplished through the study and use of contours, elevation and trigonometric points, watersheds, land use, hydrographic network, soil characteristics, geological characteristics and flood picks.

In a changing environment, due to the changing climate and the rapid urbanization, the cities have to develop the ability to be resilient and adapt in the present and future development. Therefore, every element of the urban environment has to be prepared and develop abilities, in order to face the future challenges, such as the floods. This paper focuses on a part of Kifissos drainage basin (Athens, Greece) in order to estimate and compare direct residential flood damages from different building types around Kifissos river. For the purposes of this study, FloReTo, a web-based tool was used. FloReTo is a web-based advisory system on mitigation measures on a micro-scale level, enabling tailored approach for the user’s own property data. As this paper deals with flood damages on a microscale-residential level, the data collected from the studied buildings include information concerning the type of property, the conditions of the buildings (old, new, renovated, etc.), type of foundation, elevations of the floors, configuration of the basement (if they exist) and first floor with a detailed description of the materials, the assets/property of the examined floors and finally information about the services of the building (electricity, heating, sewerage system). The comparison of the results of this model allows evaluating the predominant building types of the study area along with their preparedness and capacity to cope with the current and future challenges.

The paper Faivre et al. (2011) presents an interpretation of results deduced from two coastal cores that are trying to date the period of formation of a slightly submerged tidal notch often reported from the coasts of Istria. The development of a tidal notch in carbonate coasts is usually made possible by intertidal bioerosion processes during periods of relative sea-level stability (Pirazzoli, 1986). The inward depth of the tidal notch profile, that in Istria is often of about half a meter, may be used for a rough estimation of the duration of the period of relative sea-level stability, with assumptions on the bioerosion rates, that in the Mediterranean have been reported to vary generally between about 0.2 and 1.0 mm/y (Evelpidou et al., 2012). The profile of the Istrian tidal notch shows a well preserved roof, evidence that the notch was submerged by a rapid subsidence, probably coseismic (Evelpidou et al., 2011a, 2011b). Several publications, some of them co-signed by the same authors for the area between Porec and Zadar (Fouache et al., 2000; Faivre and Fouache, 2003), have reported, from correlation with archaeological remains, that the submerged notch corresponds, more or less, to the sea level in Roman times. Other data by Faivre et al. (2010), mention a tidal notch submerged by 0.5e0.7 m and a sea level rise from the first century AD that cannot have highly exceeded 1.0 m. Finally according to Fouache et al. (2011), the sea level rise indicated by archeological remains can be estimated at 1.0+-0.48 m since Roman times. Faivre et al. (2011) provide a new interpretation from the two cores, which is in complete contradiction with previous results, suggesting that the notch formed much later, between 1000 and 1500 AD. These two dates correspond to radiocarbon ages of two shells collected by the cores. However, apart from the depth of sampling, that nearly coincides to the base of the notch, not before but after its submergence, there is no clear evidence that the dated shells are really related to the sea level at which the notch developed before its submergence. Also, the assertion that the sample from one core would have been deposited at the beginning of the notch formation, while the sample at the same depth from the other core would just have preceded the coseismic subsidence, seems unconvincing. In fact, after the rapid subsidence of the area, the relative sea level became several decimeters higher in the areas of the Mirna River valley and of the Santa Marina Cove, permitting an acceleration in marine sediment deposition at the levels where they have been recently cored. In addition, the period between 1000 and 1500 AD seems too short for the development of the tidal notch considered, more specifically that this period seems very unfavorable to tidal notch development because the global sea-level rise that occurred until at least 1350 AD, at a rate of 0.6 mm/y (Kemp et al., 2011), has probably limited the possibilities of local bioerosion. Seismic evidence in the period around 1500 AD is also missing. If the rapid subsidence had a coseismic origin, the event is likely to have produced a tsunami in the northern Adriatic. It is hardly believable that a tsunami occurring about 1500 AD could escape notice in Venice and in the other lagoons and harbors of the western coast of the Adriatic. In short, a late Roman date, e.g. 361 AD, as suggested by Benac et al. (2004), seems more likely than a date around 1500 AD. As to the relative sea level stability necessary for the notch formation, it could have occurred in a period of balance for relative sea level changes between the eustatic, isostatic and tectonic factors (Pirazzoli, 2005), i.e. before and during Roman times, possibly in accordance with relative sea-level variations of the type of those predicted with the modelm-2byAntonioli et al. (2007, Fig. 9C or 9D).

We reassess the importance of archaeological sea level indicators along the coast of central Italy (Figure 1), recently revisited within the European COST Action ES0701. It appears that the local sea-level rise since 2000 years ago can be estimated of the order of about half a meter, that agrees with the classical literature about this topic, rather than ~1.35 m, as recently proposed. In order to analyze the contribution of glacio-isostatic adjustment (GIA) effect to sea level rise detected with observations on field, we employ different viscosity of 0.5 x 10^21 Pa.s for upper mantle and 2.7 x 10^21Pa.s for lower mantle and several late-Pleistocene ice sheets chronologies. Neglecting the tectonic contributions to sea level variations and supposing a laterally uniform rheology, in these regions, RSL curves depart from eustasy mainly because of the effects of melt water loading, responsible for a widespread subsidence reaching its largest amplitude in the bulk of the basin. The mismatch between observations from field data and model predictions can be partly attributed to the poor knowledge of the visco-elastic property of the mantle and to uncertainties of the details of the melting history. The residual between the observations and the predictions of RSL leaves some room for a contribution of recent sea level variations driven by climate change, which according to IPCC estimates amount to 30 cm globally averaged (IPCC, 2007).

A common feature of the coastal excavations in both Paros and Naxos is that of submerged antiquities and collapsed hilltops into the sea. Beach rocks along the modern coastlines bear witness to the extent and depth of ancient shores. The submerged antiquities of Paros include cemeteries of various time periods, harbor installations and certain rock-cut features whose function is not yet interpreted with certainty. The archaeologists who excavated Grotta and Aplomata on Naxos spoke of two seismic events; one at an early phase of the LH IIIA2 and another one at LH IIIC period. Indisputable evidence for those earthquakes offer two submerged tidal notches found at a depth of –3 m and –2.5 m respectively. The tsunami that covered the northern part of the Hellenistic Agora in the 2nd c. AD is additionally confirmed by a submerged tidal notch at a depth of –1.70 m and dated shells of Cerastoderma. The article proposes an entirely new perspective on the sea-level changes in Cyclades, which is strictly based on archaeological stratification and sea-level indicators.

Tidal notches are known to undercut limestone rock formations in the mid-littoral zone, especially in microtidal marine areas. Fossil tidal notches in uplifted or submerged positions have often been used to deduce former sealevel stands and tectonic movements. In particular, the good preservation of a tidal notch profile after emergence or submergence may be used as excellent evidence that the relative sea-level change was rapid, possibly coseismic. Tidal notches are believed to result mainly from marine bioerosion processes during periods of stable relative sea level. While in tropical environments their development may often include bioconstruction layers near the notch base, in temperate environment they tend to be purely erosional features, mainly caused by the boring capacity of endolithic and epilithic algae and by the grazing gastropods that rasp away the microflora together with rock particles in the intertidal range. Micro-erosion measurements have shown that the rate of deepening of a tidal-notch profile may be very variable (from less than 0.1 mm/yr to about 1 mm/yr, with averages of the order of 0.2 to 0.3.mm/yr in some sites of the Mediterranean). This high variability may depend from seasonal changes in the environment (temperature, salinity, air pressure) that have an influence not only on intertidal vegetation and grazing organism, but also on sea-level changes over seasonal or inter-annual scales. In spite of this variability, the inward depth of fossil notches may be used as an approximate method to roughly estimate the duration of a period of relative sea-level stability. All carbonate rocks are not equally sensitive to tidal-notch development: the slope of the rock layers and irregularities on the rock structure or surface may locally prevent the development of a tidal notch. This means that tidal notches may be present in some locations but not at some nearby sites. Therefore the absence of tidal notches can hardly be used as a reliable criterion to interpret the lack of a sea-level stillstand. During the last two centuries tide gauges have shown that the global sea level was rising at a rate faster than the possibilities of bioerosion. As a consequence, new tidal notches have not been forming in most places during the last couple of centuries. This is causing a general lacuna in geologic marks. In conclusion fossil tidal notches can be useful to interpret relative sea-level change in places where they are preserved. However, the lack of tidal notches does not provide evidence of the absence of a sea-level stillstand and coastal geomorphic archives are most often incomplete.

Detailed mapping along the coasts of Skyros Island (Aegean Sea) provided new evidence concerning the rates and the modality of subsidence in the area. The results are provided through the study of the shape and the dimensions of the two submerged notches detected around the carbonate coasts of the island.It is apparent that the island has been submerged not only due to the global sea-level rise during the last two centuries (1.8 ± 0.3 mm/year between 1950 and 2000), but also because of tectonic events testified by the type of the submerged notches. Some of these tectonic events seem to be of gradual and some of co-seismic origin. The transition of MSL from the retreat point of the lower notch to the retreat point of the upper notch seems to have been produced by co-seismic subsidence of about 55 cm at slightly less than 850 years BP.

The recent rise in global sea level is causing the disappearance of an important geomorphological sea-level indicator, the tidal notch.Tidal notches have often been used in carbonate coasts for Quaternary and late Holocene sea-level reconstructions and estimation of tectonic movements, especially in uplifting areas. In this paper, we review the rates of tidal notch development, and examine the recent gradual depletion of this feature, during at least the last century, and its relation to the increasing rates of sea-level rise. Some examples of tidal notch development are provided with fossil submerged notches from Greece. Although tidal notches are no longer forming in the present-day mid-littoral zone, underwater marks on carbonate cliffs may still provide evidence of submerged tidal notches corresponding to former sea-level positions, or of recent vertical shoreline displacements of seismic origin.

An underwater geomorphological survey along the coasts of six Cycladic islands (Sifnos, Antiparos, Paros, Naxos, Iraklia and Keros) revealed widespread evidence of a recent 30–40 cm submergence, part of which may have seismic origin. Comparison with information reported from earthquakes having affected the area suggests that at least part of the recent submergence might be an effect of the 1956 Amorgos earthquake. Modelling of the co-seismic and short-term post-seismic effects of the earthquake revealed that part of the observed subsidence may be explained in some of the islands by a fast post-seismic relaxation of a low-viscosity layer underlying the seismogenic zone. However far-field observations are underestimated by our model, and may be affected by a wider deformation field induced by the largest aftershock of the Amorgos sequence, or by other earthquakes.

Detailed mapping along the northwestern coastline of Euboea has provided new evidence of colonization by Lithophaga lithophaga (L.) reaching about 3.8 m above the present biological MSL. Such marine biological marks, together with morphological notches, correspond to the occurrence of two sequences of Holocene vertical displacements higher than those reported by previous studies, on the central part of the southern coast and along the northern coast of the island. A well developed emerged notch is found at + 1.7 ± 0.1 m above present mean sea level, whereas the uppermost part of the lithophagid holes suggest a former emerged shoreline at least at + 3.8 ± 0.1 m. Radiocarbon AMS dating of Lithophaga shells found in their burrows, showed that the lower uplifted shoreline corresponds to a tectonic event (probably coseismic) apparently dated at 2200 a BP, while the higher shoreline corresponds to an older relative sea-level transgression, possibly of tectonic origin, apparently dated about 5570 a BP. The apparent radiocarbon age of lithophagid shells can be about 350 to 400 years older than the uplift event that exposed them, due to incorporation of host-rock carbon. Nevertheless, the two new paleoshorelines provide evidence that repeated uplift movements, greater than those reported by previous authors, occurred during the late Holocene, uplifting the western part of the island.

Naxos Island is situated in the Cycladic plateau (middle Aegean Sea) and consists of concaved beach zones separated by small headlands. This study investigates the diachronic palaeo-shoreline shift due to the sea level change and its effect to the palaeo-environmental evolution of the western coastal part of Naxos Island during the Late Holocene. For this purpose, six boreholes were drilled and dated using radiocarbon techniques. The associated geomorphological, sedimentological and paleontological investigation concluded that during Late Holocene, the embayments of Naxos western coastal part were frequently exposed, and their communication with the sea was not perennial. The coastal area was wider with many active lagoons and embayment changing from shallow marine environment to coastal environment frequently alternating to brackish mesohaline one. The former sea-level position in western Naxos island should be between −1.5 m and −2 m during the last 2000 years, which may partly reflect eustatic processes and partly a gradual or coseismic land subsidence.

We present estimates for late Holocene relative sea level change along the Tyrrhenian coast of Italy based on morphological characteristics of eight submerged Roman fish tanks (piscinae) constructed between the 1st century B.C. and the 2nd century A.D. Underwater geomorphological features and archaeological remains related to past sea level have been measured and corrected using recorded tidal values. We conclude that local sea level during the Roman period did not exceed 58 ± 5 cm below the present sea level. These results broadly agree with previous observations in the region but contrast with recent analysis that suggests a significantly larger sea level rise during the last 2000 years. Using a glacial isostatic adjustment model, we explain how regional sea level change departs from the eustatic component. Our calculation of relative sea level during the Roman period provides a reference for isolating the long-wavelength contribution to sea level change from secular sea level rise. Precise determination of sea level rise in the study area improves our understanding of secular, instrumentally observed, variations across the Mediterranean.

Lechaion’s ancient harbor is now a coastal swamp filled with sediments. Two natural factors explain the harbor’s abandonment: (1) tectonic uplift during historical times and (2) the location of the harbor basin in a serpentine depression protected from the sea. Although it undoubtedly functioned as a very efficient sediment trap, only modest sedimentation rates (<1 mm/yr) have been measured in the basin. This paradox suggests that the basin was dredged and that the extracted sediments were dumped, forming a number of mounds around the harbor edges. The transition from marine organics to silt is dated to 750–400 cal. B.C. and precedes the 1.2 m uplift of the harbor at around 340 B.C., which underscores the minimal impact of tectonic forcing factors. The presence of fine-grained sediments is consistent with an increasingly protected environment. The macrofauna indicate a low-energy environment enriched with organic matter and brackish conditions. All data suggest that this environment became isolated from the sea. Although a seismic uplift around 340 B.C. played a partial role in the evolution of the harbor, it is not the sole natural forcing agent involved in the silting up of the basin.