Geomorphological Evolution and Fluvial System Development during the Holocene: The Case of Vouraikos River Evolution in Kalavrita Plain, Northern Peloponnese, Greece

摘要

Fluvial geomorphology is affected by physical conditions which allow its adaptation due to high dynamics and environmental influences. Fluvial morphological changes are manifested as a result of tendency of the river system to maintain its physical balance. Our study area is the upper and middle flow part of Vouraikos river and surrounding area, near the NW border of Chelmos mountain in Northern Peloponnese, near the town of Kalavrita, at an altitude of 800 m. The area is part of the Skepasto basin, constituting of a graben with a general E-W direction that was developed NW of Kalavrita. The area comprises of Mesozoic, Upper Triassic-Jurassic limestone and dolomite of the Tripolitsa unit External Hellenides and Plio-Pleistocene fluvio-lacustrine sequences, while its tectonic structure is characterized mainly by normal faults. The geomorphological landscape is characterized by alluvial deposits and important geomorphological features including fluvial terraces, alluvial fans, fluvial scarps and their main rill washes. This area has been a place of major human activity as shown by the findings of many uncovered artifacts and a settlement. Through a paleographic reconstruction, detailed field investigations, in combination with the compilation of geomorphological maps using GIS software and archaeological evidence found in the area, we attempted to reconstruct the fluvial evolution of Vouraikos river and identify the major geomorphological factors that led to, and influenced it. Finally, the link between cultural activities and sedimentary processes is also studied. The recorded environmental variations had a great impact on the geomorphological shaping and instability of Kalavrita plain and Vouraikos river and are being reflected on the buried settlement. Sediment fluxes were high enough to form strath terraces, while local tectonics aided in the strath and fill terrace creation. Smaller and younger strath terraces, formed during increased sediment supply periods, when the valley was at a higher level.