Andreas Vassilopoulos

Mapping Geomorphological Environments

Methodology-Techniques.- Fluvial Environments.- Coastal Environments.- Lacustrine Environments.- Glacial Environments.- Karstic Environments.- Volcanic Environments.- Aeolian Environments.- Surface Landforms.- Topography, Lithology and Tectonics.- Geomorphological Mapping (Case Studies).

Developing an Erosion Risk Map Using Soft Computing Methods (Case Study at Sifnos Island)

The erosional processes depend on various variables such as lithology, topography,drainage system, rock structure and climatic conditions. The quantitative evaluationof some of the above geological and geomorphological parameters is of primaryimportance for the purpose of developing erosion risk maps. These maps can becomeuseful tools for developing appropriate strategies on environmental protection, hazardassessment and regional planning.The island of Sifnos, in Cyclades, was chosen as a case study, where in the final map of the sub-basins of this island, erosion risk distribution is presented.

Holocene submerged shorelines on Theologos area (Greece)

Summary. Detailed mapping of coastline around Theologos area revealed the existence ofwell developed permanently submerged notches 75 10 cm below present mean sea level. Theregional occurrence of well preserved submerged tidal notches suggests their coseismic origin.The submergence of this Holocene shoreline possibly occurred at 1894 AD. Average submer-gence rate of 6.08 mm/yr may be estimated by a well preserved recumbent U-shaped notch.The retreating point depth suggests that the developing period of the notch might have beenof the order of as much as three thousand years.Several non in situ large rock blocks, containing marine fossils ( Lithophaga , Vermetids , Serpulids ) in growth position, seem to have been projected on the coast by a tsunami wave,which might have been caused by the same coseismic episode. Key words: notches, Sea-level changes, earthquake, tsunami, submergence rate 1 Introduction Tidal notches that usually undercut limestone cliffs in the mid-littoral zone are wellknown as precise sea-level indicators ( Pirazzoli 1986, 1996, 2005). In areas shelteredfrom wave action, elevated or submerged notches can be used to indicate former sea-level positions, with up to a decimeter confidence. The shape of the notch profilesmay also provide qualitative information on the rate of sea-level change and on tec-tonic movements.The aim of this paper is to use notches as sea level indicators to identify formershoreline positions in the area of Theologos and to show that their presence anddevelopment is associated with vertical movements of possible coseismic origin.In Section 2 the genesis of notch shapes is discussed, while in Section 3a briefpresentation of the geological setting and some archaeological and seismologicalinformation of the study area is presented. The methodology used is summarized inSection 4, while the main results obtained are presented and discussed in Sections 5and 6.2

Yria (western Naxos island, Greece): Sea level changes in Upper Holocene and palaeogeographical reconstruction

The Saint Georgios coastal zone, located at the W coast of Naxos, the largest island of the Central Aegean Sea, was investigated in order to determine the palaeo-geography, sea level changes and their effect to the palaeo-environment of western Naxos island and to human activity. Detailed geomorphological mapping, study of micropaleontological and sedimentological characteristics and dating analyses of the Late Holocene of St. Georgios coastal zone were conducted. To obtain information about the Holocene stratigraphy under the recent alluvial cover, three boreholes followed the detailed geomorphological mapping. Microfaunal analysis took place and five samples of plants, shells, peat and charred material were also collected from several layers of the sedimentary sequence and were dated using AMS and conventional radiocarbon techniques providing temporal control of the sediments. The sea-land interactions during Upper Holocene, in relation to the eustatic sea level oscillations, as well as the geomorphologic observations and analysis on deposited sediments, aims to reveal the palaeo-geographic evolution of the landscape and its impact on the archaeological sites. Sea level rise along with sea-land interactions to the landscape evolution and the transgression of sea in 6144 BP have been verified.

Palaeogeographic Evolution of the Cyclades Islands (Greece) During the Holocene

The Cycladic islands are located in the central Aegean Sea (Greece) forming a partly submerged plateau separated into two parts: the eastern shallower one (Andros, Tinos, Mykonos, Naxos, Paros, Syros, Ios, Sikinos, Folegandros) which formed one big island (6.978 km2) at the end of the last glacial period; the western islands (Kea, Kythnos, Serifos, Sifnos, Milos) which remained separated during the same period. The eastern islands constitute an erosional plateau which is the end product of a Neogene palaeosurface that was partially submerged due to thinning of the crust during the Quaternary. The presence of numerous Neolithic sites both on land and submerged indicates the existence of an advanced civilization in the area for thousands of years. The location of the lost Atlantis could be found in this area probably between Naxos, Paros and Antiparos.

Internet GIS Development for Educational Purposes

Geographical Information Systems (GIS) are important tools for various scientific aspects. Especially sciences related to cartography and geographical analysis should definitely employ GIS technology. In this study an Internet-based GIS is presented that was developed on the MapXtreme platform. This application gives access to numerous web-users through a server that controls both analysis and data retrieval requests. It is a practical and economical method in order to introduce GIS to educational institutions. This Web GIS may operate through a local or wide area network and, apart from educational purposes, offers a low cost information exchange solution between vast numbers of users.

Tafoni and Alveole Formation. An Example from Naxos and Tinos Islands

Weathering formations resembling small caves, known by the name of Tafoni, are a characteristic, but not exclusive, feature of the Mediterranean area. Examples of such geomorphological formations have been recorded in Sardinia and Corsica (Klaer, 1956; Frenzel, 1965), in Tuscany (Martini, 1978), in S. Spain (Mellor et al., 1997) and in the Aegean Sea area (Greece) (Riedl, 1991; Hejl, 2005).

Structural Control of Geomorphological Evolution of Meganissi Island (Ionian Sea) Coastal Zone and Natural Hazard Risk Detection Based on Fuzzy Sets

This chapter describes the study of the structural control of the Meganissi island coastal zone and its geomorphological evolution; based on these, it presents a coastal hazard risk map. The coastal geomorphology is affected by the lithological configuration, the tectonism, the wider seismotectonic status and the sea activity. For this study, a database has been created in GIS. using all data deriving from the above characteristics as well as from detailed fieldwork, aerial photos, satellite images and pre-existing maps. Data were analysed and processed in order to understand the geomorphological evolution of this island and its close connection with the structural evolution.

Calculating the Fractal Dimension of River Basins, Comparison of Several Methods

A new program was prepared for approximate calculation of the fractal dimension of natural objects. The program takes care to fulfill demand of the fractal theory about the minimal covering of the measured object. Three other programs are being presented for comparison and the results obtained by all of them on the same data sets are described

Study of Human Induced Recent Geomorphological and Land Use Changes of the Acheloos Delta Area in Western Greece Using GIS

This chapter studies the counteractive dynamic marine and river environments responsible for a river mouth’s and a delta’s modulation. The Acheloos River (West Greece) was chosen as the case study due to the recent changes taken place in its Delta area; the geotechnical constructions and the agricultural planning have altered the basin’s conditions. The aim of this study is to analyze the present dominant environment and the impact of human activity on this balance with the application of modern technological tools; emphasis is placed on the geomorphological along with the land use changes taking place in the three district parts of the Acheloos’ delta within a period of four decades (1960–2000): delta plain, delta front, pro delta. Bibliographic references, geographical and geological maps, aerial and satellite imagery of different seasons and dates, were utilized in addition to extensive fieldwork measurements and mapping. A geographic database was developed and it is continuously updated.