What describes a flood with a 1% chance of being equaled or exceeded in a given year?

The term that describes a flood with a 1% chance of being equaled or exceeded in a given year is known as the base flood. This statistical concept is crucial in flood risk management, and it is used in floodplain mapping to determine areas at risk of flooding. The 1% annual chance aspect indicates that, statistically, there is a likelihood of this level of flooding occurring in any given year, making it a critical threshold for planning and insurance purposes.

Base floods are often used to establish guidelines for local development regulations, funding for flood control projects, and design standards for structures within flood-prone areas. Recognizing this probability helps professionals assess risks and prepare for potential flooding events, ensuring safety and minimizing property damage.

Other choices refer to different flood-related concepts, but none represent the specific statistical definition of the base flood as accurately as this one.