How Does a Flood Form?

A flood forms in 3 ways:

  1. When dams or levees break
  2. Hurricane winds push water (A hurricane is a storm with high winds. The minimum wind speed is 200 mph.)
  3. Melting snow and heavy rain

Numbers 2 and 3 happen when the water level of a body of water goes over the height of the bank.

What is a Flash Flood?

A flash flood can occur when heavy rain and fast snow melting are in an area. This causes high water levels on roads, and that may cause crashes and traffic jams. A flash flood happens so quick that many people are unprepared when it happens.

Historical Floods

One historical flood was the 1889 Johnstown Flood. Another was the September 2014 Arizona Flash Flood.

How do These 2 Floods Compare?

These 2 floods are very different. Let's start with data from the Johnstown flood. In that flood, a city dam had broken. Days before, a storm had moved in from the west, causing 10 inches of rain in 24 hours. The town was destroyed, about 17 million dollars in damage. 2,200 people died. No reported injuries.

The September 2014 floods in Arizona caused much less damage. Heavy rain caused flash floods all over the state. In all of these floods, only 2 people died. No injuries or cost of damage reported.

Impact on Humans

Humans have learned how to prepare for future floods. Scientists have created the Doppler Radar so there will watches and warnings for floods to come. This way people will know to get to higher ground quickly. People also know they should grab a radio to listen to recent data on the flood, and to know when the flood passes.  

Fun Facts About Floods

Floods are the #1 weather related killer.

In the U.S., floods cause $133 million in damage per year.


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