Even though a "150-year flood" may occur one year,it is still possible for another of the same size to come again in the following year,or even in the same year.

Question

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The term "150-year flood" does not mean that it only occurs once every 150 years. It means that there is a 1 in 150 chance (or a 0.67% chance) of a flood of that magnitude occurring in any given year. So it is still possible for another flood of the same size to occur in the following year, or even in the same year. Each year's weather conditions and other factors determine the likelihood of a flood occurring, so the occurrence of one flood does not affect the likelihood of another in the same way that it would if the floods were caused by a fixed, deterministic process.

Even Though a "150-Year Flood" May Occur One Year,it Is