Quantification of deltaic coastal zone change based on multi-Temporal high resolution earth observation techniques

A series of methodologies are described in this paper aiming to quantify the natural hazard due to the coastal changes at a deltaic fan. The coastline of Istiaia (North Evia, Greece) has been chosen for this study as several areas of accretion and erosion have been identified during the past few decades. We combined different types of datasets, extracted from high resolution panchromatic aerial photographs and traced the contemporary shoreline by high accuracy surveying with Real Time Kinematics (RTK) GPS equipment. The interpretation of all shorelines required geo-statistical analysis in a Geographical Information System. A large number of high resolution morphological sections were constructed normally to the coast, revealing erosional and depositional parts of the beach. Retreating and extension rates were calculated for each section reaching the values of 0.98 m/yr and 1.36 m/yr, respectively. The results proved to be very accurate, allowing us to expand the developed methodology by using more complete time-series of remote sensing datasets along with more frequent RTK-GPS surveying. © 2014 by the authors

Shoreline displacement and Pineios River diversions in NW Peloponnese (Greece) as result of the geology, active tectonics and human activity during the last 100 ky

Pineios River is the 3rd longest river in Peloponnese and flows in Kyllini wider area which is located close to the Hellenic Arc-Trench system. This is one of the most seismically and tectonically active regions in Greece with a great number of changes in the morphogenetic events taking place during the neotectonic period, as well as the last 100 ky. Prior to the 18th century A.D., the lower alluvial Pineios River flowed north of the Kyllini peninsula and into the Ionian Sea southwest of Kotichi Lagoon, but the river now flows southward into a deltaic swamp and dune region, burying a former lagoon-barrier coastal zone. From this, it becomes apparent that this river is not monotonous in appearance and therefore is not completely controlled by hydrology and hydraulics. In fact, the lower alluvial Pineios River has reacted to major geological controls, surface deformation and uplift movements caused by the activity of the recently mapped Pineios normal fault zone and salt tectonics in Kyllini peninsula resulting in the river flow diversion from north to south at completely different open sea areas. The effects of the geological, tectonic and neotectonic activity and the impact of the human presence and influence on the lower Pineios River are presented in this paper in order to determine the causes of the diversion of the lower (alluvial) Pineios River (NW Peloponnese, Greece) and shoreline displacements. © 2013 Gebrüder Borntraeger Verlagsbuchhandlung

Karst collapse susceptibility mapping considering peak ground acceleration in a rapidly growing urban area

Karst collapse occurrences represent a geological hazard that can cause damage to man-made structures. In the present study, a karst collapse susceptibility map was produced using a multivariate statistical method and a Geographical Information System. The case under study is the northern suburbs of Athens (Greece). The karstic features of the study area were recorded. Physical processes (slope angle and aspect, hydrographic network, springs, lithology, tectonic features) along with anthropogenic (road network and land use) parameters were chosen as major factors affecting the karst collapse occurrences. The innovative method was combining karst collapse occurrences with seismic hazard assessment, which was achieved by calculating peak ground acceleration (PGA). The PGA was determined for a return period of 475. years, corresponding to a 90% probability of not being exceeded in 50. years. The logistic regression (LR) method was applied to evaluate these factors. Slope angle, PGA, lithology, and distance to springs and roads were statistically significant for the applied model. Among these factors, the slope angle and PGA have a negative effect, while the lithology, and distance to springs and roads have a positive effect on the karst collapse occurrences. The validation of the applied LR model indicated that the results are reliable and that the produced map is accurate. The karst collapse susceptibility map was classified into four classes. The areas of very high and high susceptibility were observed mainly in the eastern and southwestern parts of the study area. Almost 30% of the existing urban growth boundary of the study area is located in areas of very high and high susceptibility. The karst collapse susceptibility map can be used by planners and engineers for sustainable urban development. © 2013

The contribution of karstic rocks to soil quality, Ioannina plain (Epirus, Hellas)

Soil is a significant link to the food chain as trace elements and compounds are provided, directly or indirectly, to plants, animals and people. In certain areas, soil quality depends mainly on karstic rocks, such as limestone and dolomite, on which a certain type of ecosystem (karst ecosystem), is developed.Ioannina plateau in NW Hellas constitutes a large karstic basin. According to the analytical results of 112 soil samples from the plain to the north-west of the city of Ioannina, a 100km2 area, which is part of the same karstic system (polje) there is a sufficient amount of samples with over 4% of CaCO3 in about 23.20% of the sampled area. The highest values of CaCO3, water extractable and exchangeable Ca2+ and Mg2+ cations, bicarbonate (HCO3-), Cation Exchange Capacity (CEC), and pH are observed specifically in a NW-SE trending zone near to the foothills of the limestone of Mitsikeli mountain. This is mainly due to the higher supply of material, derived from the dissolution of carbonate rocks, transportation and deposition of CaCO3 of soil originating from the Mitsikeli mountain. The foothills of Mitsikeli mountain are enriched in the detritus derived from the weathering of limestone, and subsequent fluvial erosion and deposition of the calcium carbonate detritus downstream. The transport capacity of the many streams, that drain the slopes of Mitsikeli mountain, is increased, because the inclination is up to 30° and, therefore, with concurrent increase in the supply of such sediments in the eastern part of the Ioannina polje. Thus, the quality of soil in this NW-SE trending zone is definitely improved, mainly because of the supply of calcium carbonate from the aforementioned karst structure, resulting in the development of good quality soil for agricultural use and, consequently, in the development of karst ecosystem. © 2014 Elsevier B.V

Environmental research and evaluation of agricultural soil of the Arta plain, western Hellas

Soil and soil geochemical maps are powerful tools for cultivated land evaluation, agriculture management, environmental protection and land development. In this study, soil physico-chemical properties were mapped and evaluated in the Arta plain (western Hellas), including: soil texture, water extractable ions (Ca2+, Mg2+, Cl-, Na+, K+, SO42-, NO3-), exchangeable ions (Ca2+, Mg2+, Na+, K+), aqua-regia extractable elements (Co, Cr, Fe, Li, Mn, Ni, Pb, Sr, Zn and V), calcium carbonate, organic matter, Cation Exchange Capacity (CEC), soil moisture, pH, and electrical conductivity. The main natural factor controlling the chemical composition of agricultural soil of the study area is the mafic-ultramafic rocks, as recorded by the elevated Co, Cr, Cu, Fe, Mn, Ni and Zn concentrations. However, their mobility is reduced by the high clay and organic matter contents in the agricultural soil as well as the strong buffering capacity of carbonates. Another natural factor influencing the suitability of the Arta plain alluvial soil for agricultural use is sea water intrusion, as recorded by the elevated concentrations of water exchangeable Ca2+, Cl- and Na+. The spatial distribution of the water exchangeable Cl- concentrations and electrical conductivity values in the agricultural soil shows that sea water intrusion is responsible for its elevated salt contents in the coastal area. These areas, with elevated amounts of water-soluble salts, are not suitable for agricultural use since they inhibit plant growth and seed germination. © 2013 Elsevier B.V

Distribution of trace elements in stream sediments of Arta plain (western Hellas): The influence of geomorphological parameters

Stream sediment samples were collected from Arachthos River, Arachthos-Vovos Artificial Channels, Louros Artificial Channels, Louros River and Vovos River, which are located in Arta plain (western Hellas). The samples were taken in order to determine the spatial distribution of selected elements (Co, Cr, Cu, Fe, Li, Mn, Ni, Pb, Sr, V and Zn), and to evaluate the geogenic and anthropogenic factors controlling the distribution of elements in sediments. The methodology applied in this study includes geomorphological analysis, chemical analysis, factor analysis and comparison of element contents with other data sets. The weathering materials, derived from the Arachthos River's drainage basin, contribute the high element contents in the sediments of the Arta plain. The high element contents may be related with the very gentle slope of the area and the long length of artificial channels. Interpretation of factor analysis results points to geogenic (Fe-oxides, calcareous rocks with phosphorite intercalations, ophiolite fragments within deltaic deposits) and possibly anthropogenic contamination sources (intensive agricultural and farming practices), which control the element distribution in the stream sediments. © 2013 Elsevier B.V