Write notes on flooding under the following: (a) definition; (b) causes; (c) effects; (d) solution.

(a) Definition of flooding

Flooding is the overflowing of water beyond its normal channel so that it covers land which is usually dry. It occurs when the volume of water in a river, lake or coastal area exceeds the capacity of its channel or basin and spills onto the surrounding land (the flood plain).

(b) Causes of flooding

• Heavy and prolonged rainfall that supplies more water than the river channel can hold.
• Poor or blocked drainage, for example gutters and channels clogged with refuse.
• Overflowing of rivers and release of water from dams/reservoirs.
• Deforestation and removal of vegetation, which increases surface run-off.
• Building on flood plains and water channels, and rising sea level/storm surges along coasts.

(c) Effects of flooding

• Loss of lives and outbreak of water-borne diseases such as cholera.
• Destruction of property, houses, roads, bridges and other infrastructure.
• Destruction of farmlands and crops, leading to food shortage and hunger.
• Displacement of people (homelessness) and disruption of movement and business.
• Some deposition of fertile silt on flood plains (a positive effect).

(d) Solutions to flooding

• Construct and maintain good drainage channels, dams and embankments.
• Clear blocked drains and stop dumping of refuse in channels.
• Afforestation and protection of vegetation to reduce run-off.
• Prohibit building on flood plains and enforce proper physical planning.
• Public education and an early-warning system for heavy rains.