Temporal and spatial analysis of relative sea-level changes across the Emilia-Romagna coastal plain (northern Adriatic Sea)

Sea-level rise coupled with subsidence, namely relative sea level, currently represents the greatest threat to low-lying coastal areas worldwide, leading to a constant increase in flooding risks and shoreline erosion. The Emilia-Romagna coastal plain in northern Italy, facing the Adriatic Sea, is highly urbanized and critically important to the national economy. However, the entire area is prone to high flooding risks due to its low altitude and the limited resilience of the shoreline, which also results from anthropogenic modifications mainly started from the 1950s. In this study, a refined local geocentric sea-level time series for the period 1993–2020 has been reconstructed by processing data from tide gauges and satellite altimetry. Additionally, to assess the influence of vertical land movements on the relative sea level, InSAR datasets available from 2006 to 2020 have been incorporated into the analysis. After signal processing, time series representing relative sea-level changes across the entire coastal plain were produced on a spatial grid with a resolution of 500x500 meters. A relative sea level rise, ranging from 55% to 640% stronger than the geocentric one, is observed across the entire domain, with critical spots due to localized subsidence related to underground fluid exploitation, leading to severe flooding threats. • A detailed geocentric sea level time series is developed for the Emilia-Romagna coast. • InSAR data are processed to explore coastal vertical land movements over time. • Vertical land movements locally enhance the impact of sea-level rise by 55 to 640%. • Trend variability is mainly due to local, anthropogenic subsidence effects. • This approach highlights the relative sea-level change across the entire coastal plain.