What defines a regional flood?

A regional flood is characterized by widespread flooding that occurs over extensive areas due to persistent and significant rainfall over a period of time. This type of flooding typically affects larger regions rather than localized spots, accounting for the cumulative effects of several heavy rainfall events. The saturation of the soil and the resulting runoff from multiple storms contribute to the depth and extent of flooding, making it a significant event for that geographic area.

In contrast, unexpected floods from rapid snowmelt are more abrupt and singular in nature, while local floods are confined to specific areas, lacking the wider impact inherent to regional flooding. Tidal surges are also distinct, as they result from sea-level changes and are driven by tidal cycles rather than sustained rainfall. Thus, the cumulative nature and extensive geographical impact define a regional flood, aligning perfectly with the characteristics outlined in the chosen response.