Definition of Flooding
According to Ajayi (2003) define flood as a very large
amount of water that has a flow from a source such as river or a broken pipe on
a piece of land that had been relatively dry .flood is a natural occurrence
that has an adverse health implication on people and the environment. Flood can
be refers as an overflow of an expose of water that submerges land, this could
be as a result of artificial or natural causes which are in most cases
destructive.
amount of water that has a flow from a source such as river or a broken pipe on
a piece of land that had been relatively dry .flood is a natural occurrence
that has an adverse health implication on people and the environment. Flood can
be refers as an overflow of an expose of water that submerges land, this could
be as a result of artificial or natural causes which are in most cases
destructive.
According to Oxford Advanced Learner’s Dictionary 8th
edition, flood is a large amount of water covering an area that is usually dry.
Flood as a temporary rise of the water level, as in a river or lake or along a
seacoast, resulting in its spilling over and out of its natural or artificial
confines onto land that is normally dry.
edition, flood is a large amount of water covering an area that is usually dry.
Flood as a temporary rise of the water level, as in a river or lake or along a
seacoast, resulting in its spilling over and out of its natural or artificial
confines onto land that is normally dry.
Types of Flooding
Flooding are categorize into the;
1.
Coastal floods
Coastal floods
2.
Flash floods
Flash floods
3.
Harmful floods
Harmful floods
4.
Useful floods
Useful floods
1.
Coastal Floods: Low lying areas on the
coast are occasionally flooded by usually high tides punished up by strong
winds towards the shore. Another cause of coastal flood is a giant sea waves
called Tsunamis, which is caused by undersea earthquakes or volcanoes. Coastal
flooding could drive much water into the coastal area to cause damages to life
and property like tsunami of 2004.
Coastal Floods: Low lying areas on the
coast are occasionally flooded by usually high tides punished up by strong
winds towards the shore. Another cause of coastal flood is a giant sea waves
called Tsunamis, which is caused by undersea earthquakes or volcanoes. Coastal
flooding could drive much water into the coastal area to cause damages to life
and property like tsunami of 2004.
2.
Flash Floods: The most spectacular and
rapid flood are flash flood most caused when thunderstorm or hurricane bring a
short heavy burst of rain over the mountain.
Flash Floods: The most spectacular and
rapid flood are flash flood most caused when thunderstorm or hurricane bring a
short heavy burst of rain over the mountain.
3.
Harmful Floods: These types of floods not
only damage properties and crops, but also endanger the lives of human and
animals on slopes furthermore, flood water can wash away soil that clogs rivers
and streams and destroys that spraining grounds of fish. Long lasting flood
delay terrific, make sewer over flow and damage electricity and telephone
systems.
Harmful Floods: These types of floods not
only damage properties and crops, but also endanger the lives of human and
animals on slopes furthermore, flood water can wash away soil that clogs rivers
and streams and destroys that spraining grounds of fish. Long lasting flood
delay terrific, make sewer over flow and damage electricity and telephone
systems.
4.
Useful Flood: despite the fact that
there is harmful flood there is also useful flood. Floods caused by river can
be useful; when a river flows it dumps mud and sand over the land. This make a
very fertile soil called alluvial soil.
Useful Flood: despite the fact that
there is harmful flood there is also useful flood. Floods caused by river can
be useful; when a river flows it dumps mud and sand over the land. This make a
very fertile soil called alluvial soil.
Causes of Flooding
According to Park (2006) flooding is cause by
both natural and artificial factors (human activities).
both natural and artificial factors (human activities).
(A) Natural Causes of
Flooding;
Flooding;
The most natural causes of flooding are as a
result of an excessive heavy and prolonged rainfall. Storm spring tides and low
atmospheric pressure, example of area where this has occurred include (Czech
Republic and Poland in July 1997) Ogunpa in Ibadan in 1988 and 1980, Gombe
2004, Anambra in 2004, Ala River in Akure 2004 etc.
result of an excessive heavy and prolonged rainfall. Storm spring tides and low
atmospheric pressure, example of area where this has occurred include (Czech
Republic and Poland in July 1997) Ogunpa in Ibadan in 1988 and 1980, Gombe
2004, Anambra in 2004, Ala River in Akure 2004 etc.
According to the Watchtower Bible and Tracts
Society (2008), most flooded areas of the earth are as a result of topographic
arrangement by nature. Another suggestive cause of flooding is by projected
sea-level. A rise of about one meter this century mould trigger flooding over
about 18,000 square kilometres. Natural flood is a result of high frequency of
rainfall in towns and cities that are in low topographic area.
Society (2008), most flooded areas of the earth are as a result of topographic
arrangement by nature. Another suggestive cause of flooding is by projected
sea-level. A rise of about one meter this century mould trigger flooding over
about 18,000 square kilometres. Natural flood is a result of high frequency of
rainfall in towns and cities that are in low topographic area.
(B) Artificial Causes
(Factors) of Flooding:
(Factors) of Flooding:
This is as a result of improper utilization of
the physical environment. Marshal (2004) state that human activities contribute
immensely to flooding especially in the urban area.
the physical environment. Marshal (2004) state that human activities contribute
immensely to flooding especially in the urban area.
Example of artificial causes of flooding in
urbanized centres includes;
urbanized centres includes;
1. Blockage of drainage system
meant for free flow of water.
meant for free flow of water.
2. Indiscriminate dumping of
refuse into the rivers and water course which could lead to blockage of water
channels thereby causing flooding.
refuse into the rivers and water course which could lead to blockage of water
channels thereby causing flooding.
3. Deforestation activities
exposing the soil to the intense force of rainfall causing erosion and secondly
leading to flooding erosion.
exposing the soil to the intense force of rainfall causing erosion and secondly
leading to flooding erosion.
4. Open dumping is another
cause of flooding.
cause of flooding.
Floods are usually caused
by excessive runoff from precipitation or other tidal phenomena. Flood is
sometimes described according to their statistical occurrence.
by excessive runoff from precipitation or other tidal phenomena. Flood is
sometimes described according to their statistical occurrence.
When the dumps are filled and rain falls part of the refuse
are eroded to fill the public drains thereby leading to flooding. He also added
that public drains of towns and cities used as substitutes for toilet and waste
facilities can cause blockage of the drains thereby resulting to flooding.
are eroded to fill the public drains thereby leading to flooding. He also added
that public drains of towns and cities used as substitutes for toilet and waste
facilities can cause blockage of the drains thereby resulting to flooding.
Finally, the reconnaissance assessment of flooding are
by a team of experts from Delta State Ministry Of Works And Environment identified
three (3) blockage of natural drains or waterways traversing Evwreni in Ughelli
North Local Government Area of Delta state, it was also discovered by the team
that these blockages were as result of construction of illegal structure e.g.
residential buildings workshop, unprofessional agricultural practices.
Indiscriminate dumping of waste into the natural and artificial drains, weeds
and vegetation growth situation due to improper maintenance of water courses
and lack of proper connectivity of existing drainage system, culvert and
gutters.
by a team of experts from Delta State Ministry Of Works And Environment identified
three (3) blockage of natural drains or waterways traversing Evwreni in Ughelli
North Local Government Area of Delta state, it was also discovered by the team
that these blockages were as result of construction of illegal structure e.g.
residential buildings workshop, unprofessional agricultural practices.
Indiscriminate dumping of waste into the natural and artificial drains, weeds
and vegetation growth situation due to improper maintenance of water courses
and lack of proper connectivity of existing drainage system, culvert and
gutters.
Implication of Flood
Flood causes havoc and damage to the environment and
the populace, furthermore, flood damages ranges from destruction of properties,
farmlands, electrical installation, building and structures to displacement of
person and loss of human lives.
the populace, furthermore, flood damages ranges from destruction of properties,
farmlands, electrical installation, building and structures to displacement of
person and loss of human lives.
Damages caused to building and properties are usually
terrible to estimate major examples in Nigeria were the Lagos bar beach flood
in 1984-1988, 2002, and 2010 respectively as well as indiegore flood of 1981 in
Abia, Jigawa flood in 2001, Sokoto flood 2010 disaster, Agbor flood 2011 and
others across the country, extensive damages are also done to agriculture and
agricultural products by flood. In Nigeria for example, 650,000 and 440,000
hectares of agricultural land are flooded annually in Niger Delta and North
Western part of Nigeria respectively. The inhabitants of this areas where forced
to abandon their farmland and ever the entire village where flood comes.
terrible to estimate major examples in Nigeria were the Lagos bar beach flood
in 1984-1988, 2002, and 2010 respectively as well as indiegore flood of 1981 in
Abia, Jigawa flood in 2001, Sokoto flood 2010 disaster, Agbor flood 2011 and
others across the country, extensive damages are also done to agriculture and
agricultural products by flood. In Nigeria for example, 650,000 and 440,000
hectares of agricultural land are flooded annually in Niger Delta and North
Western part of Nigeria respectively. The inhabitants of this areas where forced
to abandon their farmland and ever the entire village where flood comes.
Flood not only damage properties and endanger the life
of human and animals, but have other effects as well as rapid run-off causes
soil erosion as well as sediment deposition problems down dreams, spawning
grounds for fish and other wildlife habitats are also destroy
of human and animals, but have other effects as well as rapid run-off causes
soil erosion as well as sediment deposition problems down dreams, spawning
grounds for fish and other wildlife habitats are also destroy
Health Implication of Flood
on Human and Property
on Human and Property
Flooding usually brings or
leads to infectious disease like malaria fever, dysentery, Cholera, Pneumonia,
common cold etc. (Park, 2006). People also die as a result of flood, injured
and lost of their homes, properties like electrical equipment and so on as a
result of flood. In China, the Yangzi River flooded in 1998 and 1999, as it has
done many times before but in these years, thousands of people. They were worse
than usual because people had cut down trees in the upper parts of the river.
leads to infectious disease like malaria fever, dysentery, Cholera, Pneumonia,
common cold etc. (Park, 2006). People also die as a result of flood, injured
and lost of their homes, properties like electrical equipment and so on as a
result of flood. In China, the Yangzi River flooded in 1998 and 1999, as it has
done many times before but in these years, thousands of people. They were worse
than usual because people had cut down trees in the upper parts of the river.
Prevention/Control of
Flooding
Flooding
There are three major measures for combating flooding
problem.
problem.
1. Flood Prevention: These are efforts that are
meant to prevent flood hazards rather than curbing it, such efforts include
modification of cropping practices re-forestation, terracing, contour sloughing
and disallowing bush burning.
meant to prevent flood hazards rather than curbing it, such efforts include
modification of cropping practices re-forestation, terracing, contour sloughing
and disallowing bush burning.
2. Flood Adjustment: Flood adjustment involves
accepting the loss public relief and other emergency action taken immediately
after any flood incidence immediately after a flood disaster has occur the
victims must first accept the loss arising from its occurrence after which what
follows establishment of a relief fund by the government, NGOs and private
individuals.
accepting the loss public relief and other emergency action taken immediately
after any flood incidence immediately after a flood disaster has occur the
victims must first accept the loss arising from its occurrence after which what
follows establishment of a relief fund by the government, NGOs and private
individuals.
3. Flood Minimization: Flood minimization is
mainly concerned about the river and stream channel and the purpose is to
control the flood and minimize the damage it causes by regulating it flow or
diverting it away from damaging structures or properties. The process may
involve construction of strong flood walls, dams or reservoirs, channel
improvement, dredging and dykes.
mainly concerned about the river and stream channel and the purpose is to
control the flood and minimize the damage it causes by regulating it flow or
diverting it away from damaging structures or properties. The process may
involve construction of strong flood walls, dams or reservoirs, channel
improvement, dredging and dykes.
The following have been found to be helpful in
reducing or stopping river floods.
reducing or stopping river floods.
·
Planting trees on steep slopes slows the rate at
which water flows.
Planting trees on steep slopes slows the rate at
which water flows.
·
Sometimes, a relief channel can be dug to divert
some of the flood water away from the main river.
Sometimes, a relief channel can be dug to divert
some of the flood water away from the main river.
·
Straightening the lower stretches of a river can
also help to carry flood water out to sea faster.
Straightening the lower stretches of a river can
also help to carry flood water out to sea faster.
·
In some places people build high banks called
cuvees to stop the river flooding nearby homes and land
In some places people build high banks called
cuvees to stop the river flooding nearby homes and land
·
Another way to reduce the risk of flooding is to
use a special kind of ship called a dredger, to remove mild and sand from river
bed, this depends on the river so that it can hold more water.
Another way to reduce the risk of flooding is to
use a special kind of ship called a dredger, to remove mild and sand from river
bed, this depends on the river so that it can hold more water.
References
Ajayi, P.O (2003) Comprehensive Geography
for Senior Secondary School. Ibadan: John Publisher Limited.
for Senior Secondary School. Ibadan: John Publisher Limited.
Marshal, O. (2004). A Navigational Engineer in
a Seminar Reports Compilation. London.
a Seminar Reports Compilation. London.
Park, K. (2006), Textbook of Preventive and
Social Medicine. (191h ed). India: Banarsidas Bhanot Publisher.
Social Medicine. (191h ed). India: Banarsidas Bhanot Publisher.
Watchtower Bible and Track
Society (2008). Natural Disaster. Are They Getting Worse? New York, Awake.
Society (2008). Natural Disaster. Are They Getting Worse? New York, Awake.