Flood Flood is a body of water that covers normally dry land. Most floods are harmful. They may destroy homes and other property and even carry off the topsoil, leaving the land barren. Sudden and violent floods, which leave people little time to prepare, may bring huge losses. Rivers, lakes, or seas may flood the land.
River floods are more common, though lake and seacoast floods can be more serious.
However, sometimes floods may be helpful. For example, the yearly floods of the Nile River built up the plains of Egypt and made the Nile Valley one of the most fertile regions in the world. These floods brought fertile soil from lands far to the south and deposited the soil on the Egyptian plains. Most rivers overflow their normal channels about once every two years. When a river overflows land where people live, it causes a flood.