Flood risk to population in Italy: a synoptic overview based on fatality data

Area of Science:

• Hydrology
• Risk Assessment
• Statistical Modeling

Background:

• Floods remain a significant threat to human life despite advancements in flood risk management.
• Quantifying societal flood risk, especially loss of life, is crucial for effective mitigation.

Purpose of the Study:

• To develop and test a statistical approach for modeling societal flood risk using sparse fatal flood data in Italy.
• To analyze the spatial variability of flood risk and expected return periods for fatalities.

Main Methods:

• Utilized the Zipf distribution and its parameters, estimated over a national grid.
• Employed a detailed record of 667 fatal floods across 652 sites from 1946 to 2023.
• Validated the model with a subset of the fatal flood data.

Main Results:

• Identified spatial variations in societal flood risk across Italy.
• Estimated return periods for different numbers of flood fatalities.
• Model validation showed a slight decrease in return periods for fatal floods.

Conclusions:

• The findings suggest a potential increase in localized fatal flood events, possibly linked to changing rainfall regimes.
• The statistical framework offers insights for refining flood-risk zoning and mitigation strategies.
• The approach is applicable to other countries with available fatal flood data.