During the implementation of fieldwork for the “Ecoflow” Cooperation project, in Acheloos River, Trikala Prefecture, Central Greece, 10 unstructured sediment samples were extracted from 3 sites along the river banks for measurements and analysis. The samples were taken from the areas of Drosochori (DR 1, DR 2 & DR 3), Aspropotamos (ASP 1 & ASP 3) and Mesochora (KOR 1, KOR 2, MES 1, MES 2, & MES 4). For granulometric analysis of the samples, the Folk &Ward method (2222) was used. As it was resulted, all samples are classified as gravelly sands to sandy gravels, poorly to very poorly sorted, very coarse to very fine skewed and platykurtic to mesokurtic. The ΧRD mineralogical analysis showed that in all the samples quartz is the major component. Calcite or dolomite [one sample] content is ranging between major through medium values. The presence of the magnesian calcite, which was found in two samples, is most likely attributed to biological sources (i.e. epiphytes, shells, etc), as commonly occur white colonies of small coral-like assemblages stack on the permanently wet pebbles observed close to the river banks. Sodium feldspars predominantly albite] are present in half of the samples as medium component and as trace component in the other half. By contrast, potassium feldspars [mainly orthoclase] are always present in minor/trace amounts. The presence of clay minerals, when considered as a group, is that of a medium or minor component. As the clay minerals content increases, the water has more suspended particles, so the river's turbidity during stormy events is strongly influenced. The higher content of clay minerals in the samples of Mesochora (downstream) indicates a different source of sediment from that of the other samples. By comparing the mineralogical analysis results with river water chemical analysis results from the same sampling sites, it becomes evident that the analyzed sediments do not provide the river waters with ions, as can be deduced from the low content of alkalies and alkaline earth metals. Sulphates and chlorides were detected in trace amounts in the water samples, whereas no sulphate minerals or halides there were detected in the sediments analysed. It is therefore concluded that there is not any buried evsaporite source in the vicinity of the sampling areas. In addition, the significantly low content of nitrates, nitrites and ammonia demonstrate the nonexistent contamination from biogenic factors. Another factor that plays a crucial role in the ecological status of the river is the availability of sediment for the development and maintenance of suitable habitats for the icthyofauna. The composition and structure of sediments affect their transportation and deposition behaviour which impacts the substrate of the river habitats. To assess this aspect in the study area, habitat suitability curves for specific fish species have been used that describe the best substrate for the necessary river habitats to support the breeding and reproduction of the particular fish species. The representation of the sample sediments in the substrate types required has been estimated by combining the results from habitat mapping, suitability curves and the sediment analyses. The results indicated that the type of material available in the particular river segments is appropriate for the maintenance and development of the habitat types that are required for a good ecological status.

New geomorphological investigations along the coasts of Corfu, Othonoi, Paxoi, and Antipaxoi Islands allowed the identification of recent fossil shorelines.Former sea-level positions were deduced from sea-level indicators. A ‘modern’ tidal notch, submerged c. −20 cm, was observed in all studied islands.This notch is regarded to have been submerged by the global sea-level rise that occurred during the 19th and 20th centuries at a rate exceeding thepossibilities of intertidal bioerosion. Its presence provides evidence that no vertical tectonic movements occurred since its formation. On Corfu, impactsof ancient earthquakes have left some marks of emergence at about ≥ +130 ± 11, +110 ± 11, +65 ± 11, +40 ± 11, and +25 ± 11 cm, as well as marks ofsubmergence at about −40 to −50, −85 ± 11, −120 ± 11, and −180 ± 11 cm. The emergence of +130 ± 11 cm, previously dated at about 790–400 cal. BC, was detected through erosion notches at various sites in the western part of Corfu and appears to continue even more west, at Othonoi Island. Tidalnotches submerged at depths exceeding 0.4 m were observed in the northeastern part of the island and suggest the local occurrence of a sequence offour coseismic subsidences, with average vertical displacements of 40 cm, during at least the last few millennia. At Paxoi and Antipaxoi, Holocene verticalmovements seem to have been mainly of subsidence. At Paxoi, the ‘modern’ notch was found at about −20 to −30 cm, while four more submerged tidalnotches were distinguished at about −40 ± 11, −60 ± 11, −75 ± 11, and −90 ± 11 cm, while in Antipaxoi, three submerged tidal notches were distinguishedat about −60 ± 11, −75 ± 11, and −120 ± 11 cm.

Underwater geomorphological survey may reveal evidence of submerged tidal notches. In this paper, we present the methodology with the aim to reveal past temporary standstills of relative sea-level. Some examples of tidal notch development and tectonic movements are provided from fossil submerged notches mainly from Greece. A vertical movement causes a displacement of the intertidal bioerosion zone. For this reason the tidal notch profile reflects changes that occurred in the relative sea-level. If the movement is rapid a new tidal notch will be formed. On the contrary, if the movement is slower than the intertidal bioerosion rate, the height of the notch will increase. For this reason underwater marks on carbonate cliffs may provide evidence of recent vertical shoreline displacements of gradual or co-seismic origin.

The aim of this study is to apply a state-of-the-art methodology for the estimation of environmental flows by predicting how different in-stream flows affect fish microhabitats. A habitat modelling approach was adopted to simulate and assess the ecological effects of physical aquatic habitat changes in Greek upland rivers downstream of water abstraction schemes (dams, river diversions, etc), since there is an intense debate about the construction of small hydroelectric plants in montane rivers. Two sites on the Acheloos river were chosen as study areas (Tripotamo and Mesochora upstream of the Mesochora dam), because they are located in relatively undisturbed conditions. Standard hydraulic simulation and aquatic habitat modelling was based on data surveyed along cross-sectional transects in a representative river reach. After field data collection a hydraulic model (HEC- RAS) was applied for different flows. The representative reach comprised of the habitat types and approximated proportions detected in a previous exploratory charting of hydromorphological units over a longer piece of river. Thus, a river segment for hydraulic modelling was identified in each of the study sites (segments with relatively homogeneous conditions in terms of hydrology, geomorphology, and habitats). The basic scheme of the physical habitat simulation was applied, based on a 1-dimentional hydraulic modelling, habitat evaluation with Habitat Suitability Curves (hereafter HSC) and generation of Weighted Usable Curves in function of river flow. This way, the habitat changes can be estimated for various stream flow conditions based on an indicator of habitat quantity and quality. Generic habitat suitability curves are used from Brown Trout, a relative of the native Balkan Brook Trout inhabiting local streams. In a later stage, several river flows will be integrated in the model calibration, in order to reduce the uncertainty of the model and simulate the habitat changes in terms of habitat time series within an ample range of river flows. The habitat evaluation was based on HSC; such curves are ecological models in a simple univariate format, indicating the habitat suitability of certain hydraulic conditions for a given fish species and life stage. The HSC are frequently defined by scientific studies, for the variables depth, mean velocity, substrate and cover (obtained by field observation using visual assessments by snorkelling). The habitat modelling in representative reaches enables an ecological assessment and the proposal of environmental flow regimes in the segments affected by a given water abstraction scheme. Finally, this preliminary application promotes the need for further science-based eco-hydrological approaches that are relevant to both biological quality elements and current EU policy.

The aim of this study is to describe and assess changes in physical attributes of mesohabitat types in response to different flows in a Greek mountainous river. Hydraulic simulations were applied using two one-dimensional hydraulic models, MIKE 11 and HEC-RAS. The differences between the two models were analyzed by comparing their outputs against in situ measurements. A 200 m reach in Acheloos river was chosen as study site (Mesochora upstream) mainly because it is located in relatively undisturbed conditions (near reference conditions according to the Water Framework Directive) but also because there is intense interest for the construction of small hydroelectric plants in this area and in other mountainous rivers. For the calibration process cross-sectional transects were established perpendicular to the river flow. Transects were typically placed in areas representative of the various habitat types, proportionally determined by a habitat mapping process at a larger stream segment. Each transect was permanently marked with metal rods to allow repeated measurements in time. A 2D topographic survey was conducted and field data (water level and velocity) were collected at the transects. Also, a gauging station was installed downstream of the reach in order to provide water level data in an hourly step. Hydraulic models were applied and calibrated over a range of flows and river stages using past measurements. For selecting the control transects a thorough analysis of various parameters, such as habitat representativity, streambed slope and substrate types, was applied. In this way the habitat changes were described based on various flow scenarios over time. In a later step the results from the hydraulic models will be combined with fish habitat simulation curves (HSCs) focusing on the integration of mesohabitat and microhabitat types in the environmental flow assessment scheme.

An underwater geomorphological survey along the coasts of six Cycladic islands (Sifnos, Antiparos, Paros, Naxos, Iraklia and Keros) revealed widespread evidence of seven submerged tidal notches. At least seven former shorelines were identified at depths between 280 ± 20 and 30 ± 5 cm below modern sea level. The vertical succession of several submerged notches suggests the occurrence of rapid subsidence events, potentially of seismic origin. Comparison with other sea-level indicators from Naxos and Delos islands indicates that these relative sea-level changes took place after 3300 BP and provides a rough estimate of the time of development of several submerged shorelines. The submergence of the uppermost notch at −30 ± 5 cm is ascribed to effects of the recent global sea-level rise occurred during the last two centuries and, at least in part, to effects of recent earthquakes. Potential effects of the 1956 Amorgos earthquake with regard to coseismic and post-seismic vertical displacement have been recently investigated using a modellistic approach. According to the above, the lower shorelines should result from repetitive subsidence events and not from gradual subsidence.

The 7 kilometers long coastline of Marathon Gulf (East Attica, Greece), has been chosen for this study, in order to classify its 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 area. The CVI index is used for assessing the vulnerability of a coast to an anticipated future sea-level rise. It relates geological (coastal geomorphology, historical changes of coastline’s position, coastal slopes) and oceanographic (wave height, run up and tidal range) variables in a semi-quantitative manner. We combined different kinds of datasets extracted from high resolution panchromatic aerial photographs of several time periods (1960-2010) and traced the contemporary shoreline by high accuracy surveying with Real Time Kinematic (RTK) GPS equipment. The interpretation of all shorelines required geo-statistical analysis in a Geographical Information System, in order to estimate the rate of shoreline change for a period of 53 years. Retreating rates were calculated for each section reaching the value of 0.6 m/yr. According to the produced CVI values (10.61- 39.52), it is found that 46% of the coast has very high vulnerability, 20% high vulnerability, whilst 29% have low vulnerability. The area named “Plesti” at the southern part of the study area, a large segment at the coast of Nea Makri, the northern part of Agios Panteleimonas beach and the eastern estuary of the Inois river are those with the higher risk. These conclusions are in full agreement with the field observations.

part and the Karvouni mountain in the central part. The Geology of Samos consists of a metamorphic substratum, a non metamorphic unit, neogene and quaternary sediments. This island has been affected many times by natural hazards, such as forest fires, soil erosion, flash floods and gravity movements. The aim of this paper is to create an erosion risk map of Samos Island. This has been achieved by a series of separate stages, such as the creation of a database of geological, geomorphological and topographic data, extensive field observations and analyses of aerial photos and satellite images, within a GIS based platform. The final step involves the application of a functional relationship based on a probability model to input data consisting of the lithology, slope, mean altitude, and the vegetation-land use for each drainage basin to produce the final erosion risk map.

The legislative framework in Greece regarding environmental flows is based mostly on hydromorphological criteria with little respect to the biotic elements of the rivers ecosystem. Nevertheless, the European Framework Directive (2000/60) outlines the importance of several groups of aquatic organisms that can be used as indices and provide valuable information about the water needs of the riverine ecosystem. Towards this direction, a habitat modelling approach was applied in this study to simulate and assess the alterations of the Weighted Usable Area (WUA) using existing habitat suitability criteria (HSC) for brown trout (adults and juvenile). Brown trout was selected because it is the most recreationally and economically important species in the study areas. Habitat models are designed for a wide variety of planning applications where habitat ecology is an important consideration in the decision process. Habitat Suitability Index curves used in this study describe the instream suitability of the habitat variables most closely related to stream hydraulics and channel structure (e.g., velocity, depth) for two life stages of the brown trout (adults and juvenile). The Brown Trout data are used provisionally to the complete absence of any local HSI development. For this preliminary application, depth and velocity values were converted into their corresponding habitat suitability index values using a GIS software. Among the HSC examined here, there were those that were cited by Boove (1978) and Raleigh et al (1986) and their development is based on literature sources or professional opinion. The demonstration applied here clearly identifies some of the utility in using HSC to potentially identify critical low-flow periods, where additional flow reductions may adversely affect water use, recreation, and aquatic species. The proposed method should be complemented with the ecological information of native fish species, and tested for transferability in other regions of Greece.