Remote sensing and field survey data integration to investigate on the evolution of the coastal area. The case study of Bagnara Calabra (Southern Italy)

Coastal areas worldwide are the result of a weak balance between man and the natural environment. They are exposed to strong anthropogenic pressure and natural hazard events whose intensity has increased in recent decades. In this frame, the satellite and drone monitoring systems as well as field survey are key tools to learn about the factors responsible for coastal changes. Here we describe the formation and dismantling of a fan delta at Sfalassà Stream mouth, Calabria Region (Southern Italy) to shed light on the environmental drivers modelling this coast. The flood event of 2 November 2015 placed approximately 25,000 m3 of coarse sand and gravel sediments in a few hours forming a fan-shaped delta, while three main storm surges, occurring from November 2015 to January 2016, caused its dismantling. Sentinel 2 images and several photographs captured the gradual erosion of fan delta highlighting its complete dismantling in about 3 months. The eroded sediments only partially feed the neighbouring beaches, as they were rapidly funnelled several hundred metres seaward by submarine channels whose heads cut back up at depths <10 m. This analysis showed that observing systems with high spatial and temporal resolution provide the proper knowledge to model the processes that characterise this transitional environment. They are fundamental tools for coastal zone management, which aims to ensure the sustainability of coastal zones by mitigating the effects of erosion and flooding.