Coastline changes in relation to longshore sediment transport and human impact, along the shoreline of kato achaia (NW Peloponnese, Greece)

Abstract

Coastal configuration depends upon the equilibrium between available sediment budget and prevailing nearshore wave and current conditions. Human activities often disturb this natural equilibrium by altering the sources of beach material and littoral drift pattern. In the coastal zone of the NW Peloponnese, an essentially tideless environment, the oblique approach of wind-induced waves implies an overall longshore drift from east to west. On an annual basis, the potential longshore sediment transport rates in the different sections of the study area (Kato Achaia) is estimated to vary between 0.02 10-3 m3/s and 5×103 m3/s and to fluctuate seasonally. The construction of a port and the extraction of aggregates from the R. Peiros have significantly changed the pattern of sediment transport, inducing dramatic changes in coastline configuration; thus, the part of the coastline west of the port has retreated as much as 70 m, eliminating a tourist beach, while the entrance to the port has silted up, inhibiting navigation. Coastal engineering measures, such as modification of port-breakwaters and construction of groins have made an only minimal contribution to beach recovery. Hence, coastal management plans should consider this dynamic equilibrium and protect the natural coastal system from arbitrary human activities.