The resilience of coastal systems characterized by extreme low tide phases in the Mediterranean basin

Abstract

Ongoing climate change deeply influences coastal systems, altering their natural equilibrium. Coastal systems are highly conditioned by medium and long-term processes, such as sea-level rise, the intensification of storm events, vertical land movements (natural and induced subsidence), and anthropogenic activities leading to over-exploitation of resources and structural overloads. However, low-frequency components, such as temporary atmospheric pressure anomalies, can determine peculiar situations along the coasts. This paper analyzes the coastal impacts of high-pressure anomalies affecting the entire Mediterranean region in the last years. During these events, tidal records showed a relative lowering of the sea level of about 0.2 m and, as a consequence, seaward shoreline migration of several meters was observed along the Adriatic and Tyrrhenian coasts of Italy and on the coasts of Greece. Furthermore, channels and piers dried out, as observed in Venice and Pozzuoli (Naples). Tidal signal analysis and direct field observations showed a fast adaptive response of the mobile coastal systems to this pressure anomaly, with a complete restoration of the initial conditions at the end of the event. This adaptive response reflects temporary changes in the sedimentary balance, whereas permanent processes, such as the sea-level rise and anthropogenic pressure, could determine irreversible changes that cannot be resiliently thwarted with a short-term response.