Applications of palaeoflood hydrology and historical data in flood risk analysis

Abstract

Floods are the most common natural disaster in the world and are becoming a more and more important problem with large economic losses and social disruption. Technical measures for mitigating flood impacts are included within three basic categories: predictive, preventive and corrective measures. Prevention techniques are broadly used by most of the world's flood agencies using both probabilistic and deterministic methods. In both cases, the estimation of rare, large magnitude floods is problematic due to the short gauging station records and their limited spatial distribution. Hydrologists and engineers have developed different techniques to cope with the lack of flood data by using precipitation data, regional flood information and by calculating the so called “probable maximum flood”. New developing methods on discharge estimation of past floods using geomorphological indicatiors (palaeofloods) and documentary evidence allows the lengthening of instrumental records by hundreds to thousands of years. The scientific and applied interest of these studies is evident since the estimation of return periods used for design purposes and risk planning can be supported by actual data, rather than reliance on statistical extrapolation of instrumental flood series that often record only relatively modest events.