What does the 100-year floodplain indicate?

The designation of the 100-year floodplain indicates that there is a 1% chance of flooding in any given year. This statistical measure is commonly used in flood risk assessments and helps inform land-use planning, insurance, and development decisions.

Understanding this concept is crucial because it provides a way to quantify flood risk over time. For example, while the term "100-year flood" suggests that a flood of that magnitude would occur once every century, it is important to recognize that this does not mean it can only happen every 100 years. Instead, the chance of such an event occurring in any particular year remains consistent at 1%. Therefore, properties located within this floodplain may be subject to regulations and guidelines to mitigate potential flooding impacts.

The other options represent misunderstandings of floodplain terminology and statistics, as they either overestimate or misinterpret the likelihood and nature of flooding in relation to the 100-year floodplain.