Flood is defined as an overflow of water that submerges land which is usually dry. Flooding occurs when a part of the soil or land is submerged under water. Some part of the land are prone to flooding, this is due to the soil structure
Types of Flooding
Flash floods- This occurs within a very short time and it usually as a result of heavy rain.
Rapid On-set Floods-This type of takes longer time to accumulate and the flood can last for a day or two days.
Slow On-set Floods –This is caused by water bodies overflowing their banks, it develops slowly and can last for days and weeks.
Drainage Pattern-This is a system of water course or drains for carrying off excess water. The drainage pattern in a city or town may be blocked by refuse when rain fall and water cannot flow freely in the blocked drainage.
Types of Drainage Pattern
-parallel drainage pattern
-Rectangular drainage pattern
-Dendritic drainage pattern
-Radial drainage pattern
Causes of Flooding
-Presence of impervious rock deep the soil which will not permit water to pass through them.
-Heavy downpour of rain
-Blockage of drainages
-Overflowing of water from the dam
-Natural disaster such as tsunami, earthquake and hurricane which cause disturbance to the oceans to cause flood.
-Flood can occur as a long period of rainlessness as the soil will not absorb the water.
-The melting of ice when the subsoil is still frozen.
-Absence of gutters on either side of the roads.
Prevention of Flood
-Construction of canals or drainages by government or individuals in an area with impervious rock layers surface.
-Proper drainage of rivers especially where dams are built.
-Prevention of buildings or construction of roads, houses etc. across canals, drainages and water course.
-Erection of walls along banks of river, sea and oceans to prevent tidal waves from pushing water up shore.
-Planting of trees, shrubs and grasses as this will help in breaking the power of moving floods and also reduce erosion.
-Public should be enlightened about the danger of flood and what should be done to minimize the occurrence.
Effects of Flood
-It damages houses other valuable properties.
-It can lead to loss of lives in most cases.
-It can increase the spread of disease due to contamination to water bodies.
-It makes soil infertile by removing soil nutrients.
-It reduces the available land for cultivation.
1.Release of excess water in dams can cause A.erosion B. flooding C. precipitation Evaporation
2.Where there no gutters on either side of the road…………… may occurs A. precipitation Drainage Erosion Flooding.
3.Dumping of refuse, industrial wastes in rivers can cause A. erosion B. flooding C. water movement D.rise in water level
4.Blockage of drainage and gutter can cause A.flooding Erosion Sedimentation Desertification
5.Which of the following predisposes an area to flooding? A. low rainfall B. drought C.low wind High rainfall.
6…………….. is a good example of natural disaster A.fermentation B. Rainfall C. Flooding D. Animal husbandry
7a.List four causes of flooding in your community.
b.State four methods of controlling floods.