Catastrophic Rainfall

Definition - What does Catastrophic Rainfall mean?

Catastrophic rainfall is defined as any rainfall event that exceeds the design return period or design capacity of any drainage, collection or retention system.

Typical consequences of catastrophic rainfall include flooding, landslides, and loss or damage to property. Catastrophic rainfall is usually expressed as having exceeded a predetermined design storm event, say, a 1 in 100 or 1 in a 200-year storm.

Trenchlesspedia explains Catastrophic Rainfall

Drainage systems are designed for capacities that can accommodate a predetermined storm return period. Return periods, also known as recurrence intervals, give an estimate of the statistical probability of the occurrence of the rainfall event. For instance, a 1 in 100 rainfall event would indicate that there is a 1% chance of rainfall of a particular intensity occurring in a given year.

Should the rainfall intensity exceed, for example, a 1 in 100-year storm event, the resulting rainfall could cause overloading of drainage and collection systems.

The adverse effects of catastrophic rainfall can be made worse by blockages in drainage and piping systems. Trenchless hydraulic cleaning methods such as jet cleaners, jet rodders, and high-velocity cleaners can be used to clear obstructions in drainage systems to minimize the probability of heavy flooding and damage to infrastructure.

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