Evolution of flood risk over large areas: Quantitative assessment for the Po river

摘要: Summary The worldwide increase of damages produced by floods during the last decades strengthens common perception that flood risk is dramatically increasing due to a combination different causes, among which climate change often described as major driver. Nevertheless, scientific community increasingly aware role anthropogenic pressures (e.g. steady expansion urban and industrial areas in dyke-protected floodplains) may strongly impact given area potential losses (i.e. so called “levee effect”). literature on quantitative assessments “levee-effect” or robust methodological tools for performing such still sparse. We refer floodplains middle lower portion River Po (Northern Italy), broad geographical (∼46,000 km 2 ) with two specific research questions mind: (i) has increased over half century? And, if so, (ii) what are main drivers this change? First, we assess flood-hazard evolution analyzing three long series daily streamflow available at gauging stations. Secondly, quantitatively temporal variability exposure looking time land-use demographic dynamics observed from 1950s). To aim, propose graphical Hypsometric Vulnerability Curves – HVCs) suitable assessing vulnerability large areas. Our study highlights absence statistically significant trends annual statistics stable population density within dike-protected flood-prone area. proposed flood-vulnerability indexes show residential settlements, doubled since 1950s.