Description
According to FEMA, floods are one of the most common natural hazards in the United States, affecting people in all 50 states. Floods happen when water rises outside of normal levels, overwhelming normal drainage systems.
Cause
The National Sea Grant Network says that floods occur when water draining from a watershed exceeds the capacity of the river or stream channel which would typically contain the normal flow. This increase in flow is typically caused by heavy rainfall from a large storm system or can even be caused by snow melt.
Impact
The United States Geological Survey (USGS) compiles fact sheets detailing the damage caused by flooding in America. In the late summer of 2005 alone, there was over $200 billion in estimated damage caused by flooding from Hurricane Katrina. According to the USGS, floods cause billions of dollars' worth damage each year and, on average, kill 140 people.