Floods Causes, Effects, Prevention and Control Measures
Floods occur when excess water flows over land that is normally dry. The water does not flow through any definite channel but spread over land surface. The most common type of flood is when a river overflows its banks. This may occur in the wet reason in the tropics or in spring and summer in the temperate latitudes. Another common type of flood is when ocean water overflows its shoreline and spreads over the coastal plains.
Causes of Flood
1. Heavy rainfall during the wet season.
2. Rapid melting of ice in the watershed of rivers in the temperate latitudes.
3. Collapse of dams and river embankments.
4. Poor land drainage systems, e.g. lack of drainage ditches, blocked drainage ditches, and narrow, shallow drainage ditches. Bridges and culverts that are either too low or too narrow also add to poor drainage.
5. Low relief coupled with a high water table as in flood plains, river valleys and coastal plains.
6. Strong tidal waves, storm surges and hurricanes from the sea.
7. Unplanned urban residential, commercial and industrial development on the flood plains of rivers.
Effects of Flooding
1. Destructive of farmlands.
2. Destruction of life and property.
3. Destruction of transport and communication systems.
4. Displacement of population and settlements.
Flood Prevention and Control Measures
1. Practical watershed and management such as preventing deforestation and carrying out re-forestation where necessary. Control the use of land.
2. Construction of high walls and strong embankments and the reinforcement of levees along river bank.
3. Uses of breaks to retain run-off water over land surfaces.
4. Flood plains should be used for recreational or agricultural purposes only to avoid building houses on them.
5. Construction of flood containing dams with a capacity to retain large quantities of run-off water. Such reservoirs could be used as fish ponds, sources of water for irrigation and domestic purposes.
6. Stream channelisation to increase the capacity of the channel to carry more water.
7. There should be good land use planning and development control in both rural and urban centres.
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