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

Answer Details

(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.