Long-term projections of coastal drainage under climate change and relative sea-level rise for coastal basins of Ravenna, northeastern Italy

S t u d y r e g i o n : The Ravenna coastal plain (northeastern Italy, Po River plain). S t u d y f o c u s : This study analyzes the long-term evolution of land-reclamation pumping, focusing on the Quinto and Rasponi low-lying polder basins (1977–2023), and quantifies the relative influence of hydroclimatic variability versus relative sea-level change. A non-parametric signal decomposition and multivariate dynamic regression are used to separate oscillatory variability from residual trends and to propagate the trend component under scenario-based projections through 2100. N e w h y d r o l o g i c a l i n s i g h t s f o r t h e r e g i o n : Hydroclimatic variability contributes primarily to interannual-to-decadal fluctuations in pumping, while exerting little influence on the long-term trend. In contrast, relative sea-level rise explains most of the persistent increase in pumping demand. Projections indicate that the contribution of vertical land motion to relative sea-level change is expected to decrease as subsidence rates have been decelerating and will stabilize at constant values, whereas geocentric sea-level rise becomes increasingly dominant, implying growing drainage requirements toward 2100 and increasing challenges for maintaining dry conditions and protecting freshwater resources in the Ravenna coastal basins. • Pumping records provide a 46-year time series of local coastal drainage. • Signal decomposition and statistics enabled the estimation of future drainage demand. • Climatic influence on drainage may be critical interannually but negligible in the long term. • Combined subsidence and sea-level rise drive future drainage demand. • Increasing drainage needs by 2100 threaten coastal protection and safety.