What is the ARO of a flood in a 100-year flood plain?

The correct answer is derived from the concept of the Annualized Rate of Occurrence (ARO), which is used in risk management to estimate the likelihood of a particular event occurring within a given year. In the context of a 100-year flood plain, the term indicates that there is a 1 in 100 chance of a flood occurring in any given year.

To express this statistically, the probability can be converted to a decimal to represent frequency. A 1 in 100 chance translates to a probability of 0.01 when converted (1 divided by 100 equals 0.01). Therefore, the ARO for a flood in a 100-year flood plain is indeed 0.01, which signifies that there is a 1% chance of experiencing such an event in any given year.

This understanding is crucial for effective risk assessment and management, as it helps organizations evaluate their exposure to specific risks and implement measures accordingly.