What Causes A Flood?

20 Answers

James FitzGerald Profile
There are a number of things that causes floods. The first such element is of course the weather. If we experience severe weather then there are all sorts of associated problems. If there is enough rainfall (especially over a short period of time) then the streets can become flooded and riverbanks could burst their banks. This is because as the banks swell with water from heavy precipitation there is simply nowhere else for the water to go and so the banks burst of their own accord due to such overwhelming pressure.
This can cause utter devastation to homes, fields and businesses as the sheer tide of water streams through the city. It is because the banks cannot cope with the adverse weather that there is nowhere for the water to run off and drain away.
Other reasons for floods are natural disasters such as tidal waves or tsunamis. This is caused by the sea gathering up a tremendous amount of momentum owing to a displacement of large volumes of water underneath the sea which can lead to catestrophic consequences. Two such tragic occurrences were the tsumanis emanating from the Indian Ocean that struck in December 2004, killing tens of thousands of people as well as the more recent one which hit Japan in 2011.
The situation in Japan was so severe because a previous high-magnitude earthquake caused a displacement of water which traveled across the sea and onto land, simply engulfing whole towns and villages. It is the speed of these tidal waves that caused such immense damage, not only to structures but, more importantly, to human communities due to the loss of life.
Anonymous Profile
Anonymous answered


Natural causes of floods:

1.High rainfall

Heavy rainfall raises the water level.When the water level is higher than the river bank or the

dams,the water comes out from the river,there will have a flooding.


Because of the golbal warming,the temperature of this year is higher than the temperature of many

years ago.The ice caps melt in spring,many water go into the sea.The water raises the sea level,and

makes the river level raise.When river level raises,flooding may cause.


Flooding often occurs in lowland.This is because rivers flow more slowly in low-lying area.If the

water volume increases suddenly,floods occur.

4.Coastal flooding

Flooding always occur in coastal areas.Because there have high tides or storms,the sea level will

raise.If the sea level is higher than the level of the coastal lowland,flooding will occur.

Human causes of floods:


Large areas of forests near the rivers have been cleared.The lands use to for

settlement,roads and farmland.Less vegetation protect the soil,the soil is quickly lost to rivers and

sea.This raises the river bed,so the river overflows its banks easily.Deforested area.People want

more wood to build house.So,they cut many trees.Some of the Chang Jiang's near areas are

deforested areas.

How derorestation lead to flooding:

No trees to soak up water,so more water flows into the rivers.No trees to build the soil together,so

soil erosion takes place.Large amounts of soil are washed by rain into the rivers.

Because of silting,riverbed shallower.The water volume increases,the river cannot hold all the water

and overflows its banks.

2.Poor farming

Some farming practices can damage the vegetation cover,so the soil will be washed into the river


● Overgrazing

People want more food and money,they graze too many animals on the land and the pasture

is eaten away quickly.Less vegetation cover,soil washed into the rivers easily.The areas near

Chang Jiang graze many animals.

● Overcultivation

When a piece of land has been used for farming for a long period of time,the soil may

became so infertile that no vegetation can grow on itThe land less fertile than before,so the

soil washed into the rivers more easily.

3.Poor water management

When the dams are poorly constructed or maintained ,they can easily collapse and this results in

flooding.In China,many lakes along the major rivers have been heavily silted and reclaimed,for

Example,Dongting Hu along the Chang Jiang.People want more land to farming.They reclaim the

lake,it reduces the size of the lake,it may causes flooding easily. Decreasing size of Dongting Hu ,


4.Population pressure

Because of large amount of people,everything need more,like wood,land and food Soil erosion

happen more often,it increases the risk of flooding.Large number of people live in areas with high

risk of flooding in China.They cause the problems below.Such as overgrazing and overcultivation.

d ds Profile
d ds answered
Floods occur when there is an overflow of water and the water submerges the land. Floods occur whenever the water exceeds the capacity of the container so it overflows from the boundaries. Some of the causes of flood include heavy rainfall like in monsoon season that overflows the dams, rivers and lakes. Another cause is the melting of snow on glaciers that overflows the rivers and they submerge the nearby land. In coastal areas the main cause of floods are the sea tides are high and are brought to land by heavy winds.
Hassan Raza Profile
Hassan Raza answered
Flood is a common natural disaster brought about by any of the following:

Excessive rain falls for hours or days such as during a thunderstorm or monsoon period in the tropics. The high tide especially during spring when the high tide is higher than the normal neap tide, this results in many low-lying areas in coastal regions being flooded. It occurs about the time of the new moon or full moon when the earth, sun and moon lie in a straight line and when the combined gravitational pull is at its maximum.

The melting of snow in spring also results in flooding. In a severe winter when the mountains are thickly carpeted with snow, the following spring melts the snow rapidly. The snow thaws into the water and floods the valley below.

Deforestation in the uplands, when forests are cleared on mountain slopes and there are no more roots to hold the excess water after a heavy rain, the rapid run-off erodes the topsoil and also floods the land below.

Poor drainage systems, in built-up areas such as cities and new housing estates where the drains are choked or there are insufficient outlets for the water to drain off after a heavy downpour.
Mehreen Misbah Profile
Mehreen Misbah answered
Although rivers are a great source of life and some of the most prosperous ancient civilizations depended heavily on rivers for their economy, they have their share of drawbacks too, which were existent both in the past and the present, although today their impact has mitigated by the incorporation of some precautionary techniques. For starters, rivers cause floods, which becomes an overgrowing ordeal for residents, farmers and transport authorities equally. Some of the major causes of floods are illustrated below:

The season of summer is characterized by the melting of snow, which swells the volume of the rivers and results in floods. Besides the melting snow, another source of additional water is the heavy monsoon rainfall. In addition to that, the cutting down of trees (that is generally for commercial purposes) on the foothills contributes towards augmenting surface turn-off that becomes the cause of floods. Also the embankment network along the rivers is a weak one that is built to prevent flood risk.
Anonymous Profile
Anonymous answered
It normally occurs due to either high rainfall or when the water level rises too much:)
Fesa Barrio Profile
Fesa Barrio answered
Intense rainfall, urbanization or lots of buildings, heavy storms, pollution, poor drainage systems, overflow of water and melting of snow in glaciers causes flood in different parts of the world.
Anonymous Profile
Anonymous answered
Too much rain in specific amount of  time  and  out beak of global warming,melting ice caps from  different places of the world.
E Jacobson Profile
E Jacobson answered
Floods are caused either because too much rain falls in a specific amount of time, which leads to drainage systems being overwhelmed. Or barriers such as a river bank may give way due to too much rainwater and this will cause flooding. Abnormal tides particularly combined with heavy rainfall can cause a river to burst its banks.
Flash floods are caused by too much water coming down in too short a time, with too much water to drain away effectively. Flash floods are sudden and tend to drain away quicker than other floods.

Floods may also be caused as a by product of a tsunami, earthquake or even hurricane (although it is quite rare for hurricanes to cause floods).

Parts of the UK are more liable to flooding, with over 2 million people living in a zone which is in danger of flooding. Fears are increasing tat due to global warning and subsequent weather changes, this figure may increase substantially over the next fifty years.
Anonymous Profile
Anonymous answered
It could have been caused by the outbreak of global warming, which would leads to the flooding of coastal areas and rural areas, and even leads to few big cities being completely submerged under water. Deforestation, pollution, melting of ice caps, breaking of the dams. It also could have been caused by volcanic eruptions, tsunamis, earthquakes and many other natural disasters, or even tropical storms.
Anonymous Profile
Anonymous answered
- Highly developed (urbanized) areas
- High intensities and long durations of rainfall
- Flat topography with little storage
- Poor building practices in flood-prone areas
- No replacement of lost storage as area grows

This is more precise and concise :)
Anonymous Profile
Anonymous answered
What causes a flood is when there is too much water on 1 piece of land ! Lol !

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