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Flood
Flood can cause due to any of the following or combination of the following reasons:
Excessive Precipitation: Heavy precipitation or rainfall in an area than normal along with poor drainage system can cause flood like situation. Flood can occur in both cases of heavy rainfall for shorter duration and continuous light rainfall for many days.
River Runoff: Excessive supply of water in the upstream due to heavy rainfall or otherwise can cause the downstream river water to run into the land or flood plain areas causing inundation.
Strong Coastal wind or Cyclone or tsunami: Strong coastal winds have the capacity to carry water from the sea to the land causing inundation in the coastal areas. Besides, Cyclones and strong winds can also bring heavy rainfall, causing flood on inland areas as well.
Types of Floods
Broadly floods can be classified as per timings:
Flash Floods: Flash Flood appears very fast and due to its sudden arrival, the term flash has been added to this types of flood. Flash flood cover smaller area but with high intensity, usually due to heavy rainfall or breakdown of Ice dams. Because of its higher speed and sudden appearance this flood causes more damages and is dangerous. Flash flood can even transport heavy rock, boulders and other heavy items due it its high speed. Besides, its capacity to carry debris makes this flood more dangerous as can damage both life and property.
Slow on-set Flood: This type of flood last long and spread over larger areas and occurs mainly due to over flowing of rivers or other water bodies. Since many coastal areas and flood plains repeatedly get inundated during rainy seasons, people for safety moves up to higher grounds during this period. The after effect of this flood is more dangerous as people die due to diseases and famine.
Rapid on set Flood: This type of flood occurs fast
and last for a shorter period almost for a day or two. This flood is associated
with heavy rainfall and as it appears fast the chances of damages to property
and life are high as people get less time to prepare before the flood appears.
Impacts (Problems) of Flooding
The economic Impact of Flooding
Floods like flash flood, storm surge causes huge damages to properties and
infrastructure of the affected areas. Houses, bridges, farms, roads, electric
poles and vehicles are mostly destroyed causing huge economic losses to both
public and government.
Many people losses their livelihood due to floods impact
on agricultural fields, industries etc. Due to damages in communication lines,
infrastructure and transport networks business takes hit not only in the flood
affected areas but also in the adjoining localities. The long time after
effects of flood are felt in terms of lack of clean drinking water, disruption
in power supply, reduction in purchasing power of people due to loss of income,
rise in prices of basic items etc.
Even rebuilding the infrastructure, rehabilitation of
people and bringing the normalcy in economic activities takes lot of time
causing further economic losses. For instance, the flood in Chennai, India in
November 2015 is estimated to have caused $3billion losses. As per estimation
by NOAA the flooding in 2011 in USA caused a loss of about $ 8.41 billion.
Besides if floods occurrence are regular many people and business moves out of
the place leading to mass migration, development in these places cripples as
government and private business fear of similar devastations in future due to
recurring nature of flood.
Environment Impact of Flooding:
Flooding has its
impact (both negative and positive) on the environment. Unlike the economic
impact of flooding, which is mainly negative, flooding has some positive impact
on environment. Such as refueling of surface and ground water storage.
This replenishment of water supply helps in improving the soil quality and
thus crop production. But the negative impact of flooding on the environment is
quite dangerous as the flood water brings along with it different types of
pollutants, chemicals, debris including uprooted trees, stones etc. This
polluted water contaminate the clean water due to breakdown of water pipes and drainage
systems. Besides, due to flooding many animals loses their natural habitats and
contaminated water impacts the health of livestock as well as wild animals.
Reduction in biodiversity level happens due to death and displacement of
many animals during and after flood. As noticed in Australia’s Queensland in 2011, where heavy flooding
resulted in death of many animals. The flood water once receded leave behind
debris and sediments, which also hampers the water quality.
In 2011, Tsunami struck Japan and many coastal areas got flooded including the Fukushima, where waves caused level 7 meltdown of the power plant and release of radiations due to cooling system failure by Tsunami. Nuclear radiation release has long term negative impact on the health of people, animals and the environment.
Impact of Flooding on human and animal:
The direct impact of flooding is experienced maximum by humans and animals. Flash flooding or sudden arrival of huge floods causes many damages to people and animal including loss of lives and properties. Many animals and people are forced to migrate to safer places. Post flooding rise in diseases also impacts human and animals badly.
Many people becomes homeless due to flood havoc. In addition to the physical impacts people also suffers psychologically. The flood victims can remain traumatized for longer period of time as they see all the devastation in front of their eyes. Also, by losing home and other properties the security level of people decreases they become vulnerable to many threats. The stress to rebuild the life post devastations takes further toll on human’s life.
Flood Preventive Measures
Heavy precipitation cannot be avoided as it’s a natural phenomenon. However, preventive steps to avoid flood like situations if taken timely can save both life and money. Following are some flood prevention steps:
1. Well Built and Managed Drainage System: Proper drainage system should be part of town planning. A free flowing drainage system can absorb extra water supply during heavy precipitation and avert inundation. In flood prone areas houses built at higher level should be given permission to be constructed and blockage of drainages’ and waterways by illegal construction should not be allowed. Municipalities should ensure coverage of all drains to avoid littering and resultant blockage of drainage and resultant flood like situation.
2. Increase of Vegetation Cover: More trees, grasses and shrubs should be planted in flood plains to avoid soil erosion by flowing water. Excessive flow of water can be controlled by trees, hence plantation of trees should be made compulsory in coastal areas and near water bodies such as rivers, streams and lakes.
3. Building Sea walls and gates: In coastal areas, sea walls or tidal gates can be built to control high tidal waves from entering the coasts.
4. Building of Reservoir and small detention basins: In areas where flood is recurring phenomena construction of reservoirs and dams on rivers can be done. Smaller natural detention basins or depression can also be built at rivers to drain extra flood water during the beginning of floods and give time to people to evacuate before heavy floods. For instance ‘beel’ or depression on the banks of Brahmaputra in Assam is built to capture overflowing river water.
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