GIS-based landslide susceptibility mapping models applied to natural and urban planning in Trikala, central Greece

Landslide susceptibility mapping is a practical tool in natural and urban planning; it can be applied for determining land use zones, in construction design and planning of a variety of projects. In this study, two different GIS based landslide susceptibility maps were generated in the mountainous part of the Trikala Prefecture in Thessaly, Central Greece. This was accomplished by using different methods for correlating factors, which have an effect on landslide occurrences. The instability factors taken into account were: lithology, tectonic features, slope gradients, road network, drainage network, land use and rainfall. A frequency distribution of the half number of the landslide events of the study area in each class of the instability factors was performed in order to rate the classes. Two models have been used to combine the instability factors and assess the overall landslide susceptibility, namely: the Weight Factor Model (WeF), which is a statistical method, and the Multiple Factor Model (MuF) that is a logical method. The produced maps were classified into four zones: Low, Moderate, High and Very High susceptible zones and validated using the other half number of the landslide events of the area. Evaluation of the results is optimized through a Landslide Models Indicator (La.M.I.)

Comparison of the implementation of rock engineering system and analytic hierarchy process methods, upon landslide susceptibility mapping, using GIS: A case study from the Eastern Achaia County of Peloponnesus, GREECE

As landslides are very common in Greece, causing serious problems to the social and economic welfare of many communities, the implementation of a proper hazard analysis system will help the creation of a reliable susceptibility map. This will help local communities to define a safe land use and urban development. The purpose of this study is to compare the implementation of two semi-quantitative landslide assessment approaches, using landslide susceptibility maps compiled in a GIS environment. The compared methods are rock engineering system (RES) and the analytic hierarchy process (AHP). For the landslide susceptibility analysis, the Northeastern part of the Achaia County was examined. This area suffers from many landslides, because of its neighborhood with the tectonically active Corinthian Gulf and its geological setting (Neogene sediments, flysch and other bedrock formations, with local overthrusts). Ten parameters were used in both methodologies, and each one was separated into five categories ranging from 0 to 4, representing their specific conditions derived from the investigation of the landslides in the western part of the study area (ranking area). A layer map was generated for each parameter, using GIS, while the weighting coefficients of each methodology were used for the compilation of RES and AHP final maps of the eastern part of the study area (validating area). By examining these two maps, it is revealed that even though both correctly show the landslide status of the second site, the RES map reveals a better behavior in the spatial distribution of the various landslide susceptibility zones. © 2010 Springer-Verlag

The spatial distribution of middle and late pleistocene cirques in Greece

In Greece, Middle to Late Pleistocene mountain glaciations appear to have been quite extensive, along the mountain range of Pindus, on Mt Olympus and in the highlands of Peloponnesus and Crete. This study focuses on the extent of the Middle to Late Pleistocene glaciations in Greece based on the examination of cirque formations. An initial spatial database of these glacial forms was created for the first time in Greece, including cirque location and morphometric properties. In total, 265 cirques were recorded covering a total area of 94.9km2 with limestone as the dominant underlying lithology. The number of cirques has decreased in southern Greece. Cirques occur at altitudes ranging from 2770 to 1600m a.s.l. The largest cirque areas are observed in northern Greece. Since several highlands of Greece have uplifted, the mean elevations of these cirques have increased in time. In northern Greece the cirques are wider, longer and deeper. The vast majority of cirques are facing towards the northeastern hemisphere due to more severe climatic conditions originating from the northeast during glacial periods. © 2014 Swedish Society for Anthropology and Geography

Flood hazard assessment mapping in burned and urban areas

This study proposes a simple method to produce a flood hazard assessment map in burned and urban areas, where primary data are scarce. The study area is a municipal unit of Nea Makri, a coastal part of the eastern Attica peninsula (central Greece), which has been strongly urbanized and suffered damage from urban fires in 2018. Six factors were considered as the parameters most controlling runoff when it overdraws the drainage system’s capacity. The analytical hierarchy process (AHP) method and a geographical information system (GIS) were utilized to create the flood hazard assessment map. The outcome revealed that the areas with highest flood hazard are distributed in the eastern and southern parts of the study area, as a result of the combination of lowlands with gentle slopes, torrential behavior of the streams, streams covered by construction, increasing urbanization and burned areas. The uncertainty and the verification analyses demonstrate a robust behavior for the model predictions, as well as reliability and accuracy of the map. Comparing the existing urban fabric and road network to the potential flood hazard areas showed that 80% of the urban areas and 50% of the road network were situated within areas prone to flood. The method may be applied to land use planning projects, flood hazard mitigation and post-fire management. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

The significance of tectonism in the glaciations of Greece

Glaciers were common features in the highlands of Greece during the Middle to Late Pleistocene glacial periods and cirques are characteristic landforms of mountain glaciation. This study examined the cirques of Greece and the role of tectonic uplift in determining their altitude across the country, from Mount Olympus to the Peloponnesus and Crete. An inventory of 227 Middle to Late Pleistocene age limestone cirques was compiled. The number and total area of the cirques decreased from northern mainland Greece (Macedonia, Epirus) to the south (the Peloponnesus, Crete) and on moving to higher elevations. Continued tectonic uplift of the Olympus massif, the Peloponnesus and Crete has led to altitudinal changes in cirques in every subsequent ice age. The formation of cirques at lower elevations during Marine Isotope Stage 12 suggests extreme climatic conditions. On Mount Olympus, the mean elevation of cirques was estimated to have increased by c. 450 m since Marine Isotope Stage 12; in the northern and southern Peloponnesus the elevation increased by c. 500 m and 190 m, respectively, and in Crete by c. 400 m. The cirques have uplifted at approximately the same rate in northern Greece, but at different rates in southern Greece during this period. © 2017 The Author(s). Published by The Geological Society of London

Temporal and spatial analysis of flood occurrences in the drainage basin of Pinios River (Thessaly, Central Greece)

Historic data and old topographic maps include information on historical floods and paleo-floods. This paper aims at identifying the flood hazard by using historic data in the drainage basin of Pinios (Peneus) River, in Thessaly, central Greece. For this purpose, a catalogue of historical flood events that occurred between 1979 and 2010 and old topographic maps of 1881 were used. Moreover, geomorphic parameters such as elevation, slope, aspect and slope curvature were taken into account. The data were combined with the Geographical Information System to analyze the temporal and spatial distribution of flood events. The results show that a total number of 146 flood events were recorded in the study area. The number of flood events reaches its maximum value in the year 1994, while October contains the most flood events. The flood occurrences increased during the period 1990-2010. The flooded area reaches its maximum value in the year 1987, and November is the month with the most records. The type of damages with the most records is for rural land use. Regarding the class of damages, no human casualties were recorded during the studied period. The annual and monthly distribution of the very high category reaches the maximum values, respectively, in the year 2005 and in June. The analysis of the spatial distribution of the floods proves that most of the occurrences are recorded in the southern part of the study area. There is a certain amount of clustering of flood events in the areas of former marshes and lakes along with the lowest and flattest parts of the study area. These areas are located in the central, southern, south-eastern and coastal part of the study area and create favorable conditions for flooding. The proposed method estimates the localization of sites prone to flood, and it may be used for flood hazard assessment mapping and for flood risk management. © 2018 by the authors

Multi-criteria decision analysis for an abandoned quarry in the Evros Region (NE Greece)

The purpose of this study is to identify the impacts of abandoned quarries and to examine scenarios for their restoration. Two quarries were selected as case studies, which are located in the Evros Region (NE Greece). Initially, the current state of the abandoned quarries was recorded and evaluated, including slopes, landscape, land use, as well as cultural elements. Four alterative scenarios for the exploitation of each quarry were proposed, taking into account the specifics of each site. Financial, environmental, and socioeconomic criteria were then used to evaluate these scenarios. The PROMETHEE method is a multi-criteria decision analysis approach and was applied to rank the alterative scenarios. The results show that the "do nothing" scenario is the worst solution for both quarries. In the quarry at Asvestades, the restoration of the area by returning the land to pre-quarry use with the shaping of the slopes and planting is considered the best solution. On the other hand, in the quarry Mikro Derio two scenarios are proposed; one provides restoring the site to its pre-quarry land use and the other is the restoration of the quarry combined with the creation of a wildlife observatory and places for alternative forms of tourism. © 2018 by the authors