When it comes to property and lives lost, floods come in second to tornadoes as one of the top natural disasters. In fact, in 2011, it was reported the U.S. flood damages totaled
to $8.41 billion. Floods can affect any area wherever rain falls. Water can even come in the form of snow and seep into the ground. If the ground is frozen or impervious (materials such as asphalt or concrete), the moisture does not absorb and problems arise.
Floods can affect both small areas of land as well as vast areas. Many have been know to impact entire islands and river basins.
Floods can be as a result of overflowing rivers, extreme coastal events, or even ground saturation from too much rainfall.
If river flooding exceeds the capacity of it’s channel, flooding of all of the surrounding area may occur.
Flash floods can occur quickly, without warning and with little to no excessive rainfall.
Areal floods happen when low-lying impenetrable ground (such as drought hardened, concrete paving or frozen farmland.) is saturated with rain that cannot run off as quickly as the water accumulates.
Depending on the type, floods can very develop slowly over time after there has been extensive rains or in just a few minutes without any sign of rain.
Coastal flooding is caused by high sea tide surges that damage coastal defenses. In some cases, this damage is caused by hurricanes, tsunamis or tropical cyclones.
After floodwaters have receded, land may be contaminated with various hazardous material, such as debris from buildings, fuel and even untreated sewage. Residents have no power or clean drinking water and this leads to outbreaks of disease.
Advanced computer modeling gives authorities the ability to predict where the flooding is likely to occur as well as how severe it is going to be.