Flood/Inundation

Definition

Flood is a temporary condition of partial or complete inundation of normally dry land areas. Floods arise from an overflow of inland water or tidal waters or the unusual accumulation and runoff of surface waters from any source. Sometimes flood events involve abnormal, flood-related erosion and undermining of shorelines. Flood also means inundation from mud flows caused by accumulations of water on or under the ground [*1].

Context

Flooding is the most common environmental hazard worldwide, after disease and transport accidents [*2].

Floods:

  • affect 20 million people every year
  • induce severe losses of lives
  • induce homelessness
  • induce large economic losses

River flooding is essentially a natural process, which occurs when excessive rainfall (or melting snow) exceeds the ability of land to drain the water effectively [*3].

Such an event is not a hazard unless it threatens human life and property!

The degree of flood hazard, or so-called hazard intensity, depends on:

  • flood water depth
  • water flow velocity
  • flood duration
  • velocity of water rise
  • flood water load (sediment, salts, sewage, chemicals)
  • river bank erosion
  • rise of groundwater

Flood processes have a direct impact on the ecosystem services [*4]. Furthermore floods can have negative and positive impacts on societies [*5].

Methodology

Example

For examples of different types of flood click here.

Assessment


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Source

TUHH

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References

*1 Munich RE- 1997

*2 Smith (2004)

*3 Kass et al. (2002)

Downloads

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Further Information

Tutorial:

*4 Flood processes and ecosystem services

*5 Positive and negative impacts of flood on societies