Large amounts of rainfall or the fast melting of snow getting into a river can cause floods. These two factors let excess water overflow the river banks into land near the river. River floods vary in strength, depending on the amount of excess water. Fast river floods are also called flash floods and can happen very quickly. The village of Boscastle in the United Kingdom was hit by a severe flash flood in August 2004, which carried cars, trees and even buildings into the sea. The rapid flow of water through the village forced people onto the roofs of their homes, and authorities eventually sent helicopters to rescue them.
Coastal floods usually happen when high winds and large waves combine with a high tide to cause water to advance onto dry land. Since storms cause it, this type of flooding is also referred to as storm surge flooding. In 1953, a particularly devastating coastal flood, called the North Sea Flood, affected the U.K., Netherlands and Belgium. A high spring tide, combined with a storm and extremely high winds, caused sea levels to rise rapidly and overwhelm sea walls. Water covered large areas of land, and as a result of the flooding, homes and businesses were destroyed, and more than 2,500 people died.
Probably the most dangerous type of flooding occurs when a tsunami hits an inhabited coastal area. Underseas earthquakes send out huge waves, called tsunamis, that hit land with devastating effects. Tsunami waves push sea water inland at high speeds, rapidly flooding land near the coast. A tsunami that originated in the Indian Ocean caused deadly flooding on Dec. 26, 2004. Indonesia was the most badly hit country by this tsunami, with entire villages wiped out. The sea water surged inland with such force and speed that many people did not have time to get to higher ground.
Human activity that tries to manipulate or manage water flow can also cause floods. At one end of the scale, a water pipe broken by workmen could flood homes near the affected pipe. On the other end of the scale, a human-made dam could fail and let large amounts of water rush into an inhabited area. This scenario happened in the Buffalo Creek Flood, which struck in West Virginia on Feb. 26, 1972. A dam used at a coal mining facility burst open just four days after being approved by a federal mine inspector. The resulting deluge of water crested at over 30 feet high as it tore through 16 coal miner settlements in Buffalo Creek hollow.