This water treatment plant in Des Moines, Iowa, was flooded by the Raccoon River in 1993. Flooding was a serious problem all over the United States that year due to rainfall amounts far above average. AP/Wide World. Reproduced by permission.

Floods can be defined as an overflow or downpour of water accumulating in an area where water is normally absent. Floods usually occur within a short period of time due to the soil's inability to absorb the water fast enough. According to the United States Geological Survey, floods were the natural disaster that caused the highest number of deaths and the most property damage in the United States during the twentieth century. Of all the natural disasters, floods are the most common and occur in the most places, with the only exception being fire. Flooding results in heavy currents that have the capacity to loosen structures and collapse...