Flood is an overflow of water that submerges or "drowns" land.
Flooding may result from the volume of water within a body of water, such as a river or lake, which overflows or breaks levees, with the result that some of the water escapes its usual boundaries, or may be due to accumulation of rainwater on saturated ground in an areal flood..
Floods can also occur in rivers when the flow rate exceeds the capacity of the river channel, particularly at bends or meanders in the waterway. Floods often cause damage to homes and businesses if they are in the natural flood plains of rivers.
Floods can happen on flat or low-lying areas when the ground is saturated and water either cannot run off, or cannot run off quickly enough to stop accumulating.
This may be followed by a river flood as water moves away from the floodplain into local rivers and streams.
Localised heavy rain from a series of storms moving over the same area can cause areal flash flooding when the rate of rainfall exceeds the drainage capacity of the area.
When this occurs on tilled fields,it can result in a muddy flood where sediments are picked up by run off and carried as suspended matter or bed load.
Damage to buildings and other structures, including bridges, sewerage systems, roadways, and canals.
Infrastructure damage also frequently damages power transmission and sometimes power generation, which then has knock-on effects caused by the loss of power.
This includes loss of drinking water treatment and water supply, which may result in loss of drinking water or severe water contamination.
It may also cause the loss of sewage disposal facilities.
Lack of clean water combined with human sewage in the flood waters raises the risk of waterborne diseases, which can include typhoid, giardia, cryptosporidium, cholera and many other diseases depending upon the location of the flood.
