Historical comparison of the damage caused by the propagation of a dam break wave in a pre-alpine valley

Study region: Valle Camonica basin and Lake Iseo in the Italian pre-alpine and alpine region. Study focus: This paper provides the first hydraulic reconstruction of the terminal part of the Gleno dam break with the propagation of the flood wave along a wide pre-alpine valley. The reconstruction of this part of the event, accomplished with a new 2D Shallow Water Equations solver, provides the occasion to tackle some important issues related to the computation of flood damage, a topic of paramount practical importance for which there is no widely accepted procedure in the literature. New hydrological insights for the region: The hydraulic reconstruction provides insights into the propagation of the flood through the floodplain as far as the inlet of Lake Iseo. A methodology for damage computation is presented that considers a physically based criterion for the vulnerability of human life, with significant implications with respect to the use of simpler approaches based only on the density of the population. The economic evaluation of the damage to the built environment and to agricultural activities is included through a comprehensive recent approach. We discuss the variations of the expected damage due to the hydraulic works accomplished over the last 100 years to decrease the flood hazard, showing that its reduction has been followed by an increase in the expected damage in the surrounding areas.