Water is one of the most useful resources on Earth. We drink it, bathe in it, and cook with it; but in large enough quantities, water can overturn cars, destroy homes and even kill. We will never be able to stop flooding. We can only minimize the damage it causes by building sophisticated dams, levees and canal systems. Of course, the best way to avoid flood damage is to avoid building homes in flood-prone areas.

What is a Flood?

A flood is a natural disaster that occurs when there is more water than a lake, river, creek or even the ground can handle.

A flash flood is sudden flooding that occurs when floodwaters rise rapidly with no warning within several hours of an intense rain. Flash floods usually happen after heavy rainfall from a slow moving thunderstorm.

Types of Floods

  • 10-Year Floods
  • 100-Year Floods
  • 500-Year Floods

The terms 10-, 100- and 500-year floods do not mean it floods every 10, 100 or 500 years.

A 10-year flood has a 10% chance of happening in any given year, a 50-year flood has a 2% chance and a 100-year flood has a 1% chance, while the 500-year has only a 0.2% chance.

The chart below shows the chance of flooding in a high risk area over varying periods of time.

Chances of Being Flooded

Period of Time

10 yr. flood

25 yr. flood

50 yr. flood

100 yr. flood

1 year

10%

4%

2%

1%

10 years

65%

34%

18%

10%

20 years

88%

56%

33%

18%

30 years

96%

71%

45%

26%

50 years

99%

87%

64%

39%