There are two basic types of floods. In a river flood, water slowly climbs over the edges of a river. The more dangerous type, a flash flood, occurs when a wall of water quickly sweeps over an area. Almost three-quarters of deaths from floods each year are due to flash flood
Floods incur millions of pounds in financial losses each year.

Floods are not always disastrous, however, as in the case of the Nile River before the Aswan Dam was built. The Nile flooded every spring bringing much needed enrichment and moisture to the fertile soil of its floodplains.

[Drought]