洪水重现期，也称为重现间隔或重复间隔，是事件发生之间的平均时间或估计平均时间。 它是一种通常基于长期历史数据的统计测量，通常用于风险分析。该指标描述了在概率定义的时间范围内，危险事件以特定强度或以上发生的可能性。

Flood return period, also known as a recurrence interval or repeat interval, is an average time or an estimated average time between events to occur. It is a statistical measurement typically based on historic data over an extended period, and is used usually for risk analysis. They describe how likely a hazard event is to occur at, or above, a specific intensity within a time frame defined by a probability.