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

𝑆𝑡𝑢𝑑𝑦𝑟𝑒𝑔𝑖𝑜𝑛: The Ravenna coastal plain (northeastern Italy, Po River plain). 𝑆𝑡𝑢𝑑𝑦𝑓𝑜𝑐𝑢𝑠: 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. 𝑁𝑒𝑤ℎ𝑦𝑑𝑟𝑜𝑙𝑜𝑔𝑖𝑐𝑎𝑙𝑖𝑛𝑠𝑖𝑔ℎ𝑡𝑠𝑓 𝑜𝑟𝑡ℎ𝑒𝑟𝑒𝑔𝑖𝑜𝑛: 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.