Whether from overflowing rivers, rising groundwater, or sea-based storms, flooding affects every corner of the country, and is the most prevalent natural disaster facing United States homeowners. Even those living away from high-risk areas are not immune – nearly 25% of flood insurance claims come from residents who may have expected that they were safe.
Here are a few of the more common causes for catastrophic flooding:
- Heavy Rainfall
As rivers and other channels rise above their banks, standing structures are at serious risk. Water can easily permeate the ground surrounding your home or business, leading to damaged property and even weakened foundations. Risk in colder regions may be elevated in the winter and early spring, as frozen soil is already ineffective at absorbing and trapping water.
- Springtime Thawing
Speaking of frozen soil: as warm weather returns to melt existing snow and above-ground ice, a considerable swell of liquid returns to the water table in a relatively short amount of time. This runoff, unable to easily soak into the icy earth, may flow into residential areas and/or into surging rivers, causing potential complications for property owners.
Another direct cause of flooding is the rupturing of large natural or man-made dams and levees that restrict bodies of water. Reservoirs, rivers, and even oceans may unload their contents on endangered homes and businesses. When occurring out at sea or even in large lakes, earthquakes also can cause considerable waves (known as tsunamis or seiches, respectively) that result in significant coastal damages.
- Hurricanes, Tornadoes, and other Large-Scale Storms
The United States faces seaborne storm risks along both the Atlantic and Pacific coasts, and hurricane season for each tends to run from late spring through mid-autumn (with peaks in late summer). These storms bring tidal surges and massive rainfall to afflicted regions, and may compound the problem by damaging levees, storm breaks, and reservoir walls. Even tornadoes – perhaps more famous for their wind and airborne debris – may bring increased rain and cause similar damages.
Homeowners may be surprised to learn that fire – perhaps considered by some to be the polar opposite of water – can actually put them at risk for flooding. The fact is that as wildfires destroy large swaths of vegetation and burn the underlying soil, ground in the afflicted area becomes less effective at soaking up rainwater. Those living downhill from blaze sites face potential danger from floods and mudslides.
Note that in the United States, regions in and around the West Coast are most likely to see catastrophic wildfire – the National Fire Protection Association has prepared a wildfire-risk reference map.