Flood-induced ground effects and flood-water dynamics for hydro-geomorphic hazard assessment: the 21–22 October 2019 extreme flood along the lower Orba River (Alessandria, NW Italy)

The knowledge of flood-induced ground effects and flood-water dynamics is a crucial issue for hydro-geomorphic hazards assessment mapping, thus river management land use planning. This paper the related 1:15,000 map illustrate lower Orba River (NW Italy) its adjacent floodplain geomorphic response to 21–22 October 2019 extreme flood. was estimated be 500-years flood caused severe damage cultivated fields, structures, infrastructures. research based on extensive post-flood field surveys, ante- GNSS aerial photographs interpretation. Intense in-channel sediment mobilization, bank retreats, channelization structures collapses were surveyed. Furthermore, alluvial gullies, overbank deposits, crevasse splays, surficial-erosion evidences mapped over floodplain, along with flooded area (17.65 km2) features. A specific legend developed flood-related anthropogenic elements mapping in typical lowland agricultural landscape regulated rivers proposed.