Hundreds of satellite images spanning over 25 years have been compiled to show the evolution of Greece’s ever-changing coastlines.
For decades, coastal areas have been subject to intense urbanisation and population growth. These areas are some of the most dynamic on Earth and, unfortunately, suffer from severe coastal hazards owing to storm activity and sea level rise. Monitoring coastal areas is key to understanding the evolution of coastal dynamics and in helping authorities protect these environments.
The Space for Shore project, funded by ESA, provides a variety of tools for coastal erosion monitoring using Earth observation products. The consortium is composed of technical experts from five European countries.
Two key players of the consortium, Terraspatium and i-Sea, have processed hundreds of satellite images, including data from the Copernicus Sentinel-2 mission, from 1995—2020 to analyse over 900 km of coast in Greece – in the Peloponnese, Eastern Macedonia and Thrace regions.
The results highlight the fragility of Greece’s coastline and indicate the likelihood of coastal erosion increasing in the coming years. Over the 1995—2020 period, around 40% of the coastlines analysed have shown ‘progradation’ which is the seaward growth of beaches caused by the progressive build-up of sediment. The team found that nearly 10% of the studied coastal areas are subject to erosion greater than 3 m per year.
Deltas, estuaries and capes appear to be the most exposed areas with retreat that can reach 30 m per year. Erosion at river mouths are especially of great concern as this signifies a sediment deficit and suggests critical and long-lasting consequences for coasts deprived of sediment input from rivers.
The high-frequency monitoring of nearshore bathymetry is key in sediment management and coastal engineering. The analysis shows that changes in the nearshore bottom slope, sandbar migration or even an overall increase in depth, are all worrying signs of sediment shortage that can forewarn or aggravate coastal erosion.