CISSP · Question #510
CISSP Question #510: Real Exam Question with Answer & Explanation
The correct answer is B: The odds of a flood at this level are 1 in 100 in any given year.. The '100-year floodplain' is a statistical concept describing annual flood probability, not a time interval between floods. It refers to a 1% annual chance of flooding, which emergency planners use to assess risk zones.
Question
What does the term "100-year floodplain" mean to emergency preparedness officials?
Options
- AThe area is expected to be safe from flooding for at least 100 years.
- BThe odds of a flood at this level are 1 in 100 in any given year.
- CThe odds are that the next significant flood will hit within the next 100 years.
- DThe last flood of any kind to hit the area was more than 100 years ago.
Explanation
The '100-year floodplain' is a statistical concept describing annual flood probability, not a time interval between floods. It refers to a 1% annual chance of flooding, which emergency planners use to assess risk zones.
Common mistakes.
- A. This reverses the meaning entirely - a 100-year floodplain identifies an area at risk of flooding, not one that is protected or safe from it.
- C. This incorrectly implies a deterministic timeline for the next flood; flood probability is an independent annual probability, meaning a major flood could occur in consecutive years or not for centuries.
- D. The designation has nothing to do with historical flood records or when the last flood occurred; it is a forward-looking statistical risk assessment based on hydrological modeling.
Concept tested. Annual flood probability and floodplain risk designation
Reference. https://www.fema.gov/glossary/one-percent-annual-chance-flood-hazard
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