Declassified and historical Remote Sensing data for reconstructing fluvial landscapes submerged by dams in climate-sensitive regions

Dams profoundly modify pristine fluvial landscapes, altering hydrological processes, sediment dynamics, and landform development. To reconstruct these significant changes, we propose a methodology based on the interpretation of multitemporal remote sensing datasets. This approach integrates historical maps (late 1800s–early 1900s), aerial photographs (1930s–1950s), declassified Corona satellite imagery (1967–1968), and modern satellite data (Landsat, Sentinel, WorldView) into a workflow that enables the reconstruction of pre-dam landscapes and the quantification of geomorphic changes over time. This approach has been applied and tested in contrasting morphoclimatic settings substantially impacted by reservoir creation: the Cancano–San Giacomo and Livigno dam systems in a high-mountain region of the Central Italian Alps, and the Mosul Dam reservoir along the Tigris River in arid northern Iraq. Despite their contrasting climatic contexts—temperate alpine and semi-arid—both systems exhibit high geomorphic sensitivity to perturbations in fluvial dynamics. In the Cancano–San Giacomo area, 20th-century damming submerged the upper Adda Valley, leading to terraces formation, slope reconfiguration, and the disconnection of tributary streams. At the Livigno reservoirs, anthropogenic reshaping has involved shoreline stabilization, sediment redistribution, debris flow modulation, and deltaic progradation under regulated flow conditions. In the Mosul basin, declassified Corona imagery reveals the seasonal dynamics of the Tigris River prior to inundation, documenting a shift from meandering to anastomosing patterns and highlighting the strong litho-structural control over the reservoir’s current morphology. The results underscore the importance of inherited fluvial architectures and geological settings in shaping dam-induced landscape transformations. Remote sensing—particularly historical and declassified sources—proves invaluable for reconstructing geomorphic baselines. This work highlights the significance of identifying and analyzing submerged terrestrial landscapes, which serve as crucial archives for understanding long-term human impacts on river systems and for informing future assessments in environmentally sensitive areas.