Flash floods are among the world’s deadliest natural disasters with more than 5 000 lives lost annually. Their social, economic and environmental impacts are significant. Accounting for approximately 85% of flooding cases, flash floods also have the highest mortality rate among different classes of flooding, including riverine and coastal. Flash floods differ from river floods in their short time scales and occurrence on small spatial scales, which makes flash flood forecasting a different challenge from large-river flood forecasting.
