Flood, this five letter word is not new to us, it is one of the natural disaster. Some of us knew about the flood by book and some have experienced it. When there is an overflow of water and submerges a dry land we call as floods. The floods that we talk about will occur instantly and also slowly. Normally, flood is caused due to heavy rainfall, dam breakage/opening due to huge water inflow into dams, snow melt and storm surge.
In my native place to reach the city, we have to cross a bridge over river Amaravathi. Most of the time the river has very less water that the banks are wide open with sand, but there was a time when I was a little girl, I was able to notice that the river has a nice flow of water due to heavy rain in the catchment area and day by day the water level started to rise and in a week or so the water was overflowing the river banks. This was my first experience with floods, but from a safe distance. This type of river overflow is known as river flood.
As you can see in the fig. 1. this kind of river flood is caused due to heavy rain in the catchment area or snowfall that causes the river to overflow. Submerging the adjacent area.
Fig. 1. River flood
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There is another kind of flood that is caused due to heavy rain in upslope area, flood occurs within six hours of rain as the water submerges, low lying area due to the topographical location of the place and also due to urbanization that results in poor drainage system. These kind of flood that occur in a brief period, causing extensive damage are flash floods. These also occur when there are dam breaks.
In Fig.2. on your left side, you can see how the flash flood occurs and results in urban flooding. These floods cause extensive damage as there is very less reaction time.
Fig. 2. Flash floods and surface water floods
Image source: https://www.zurich.com/
Most of the major cities with poor drainage system experience urban flood. With the news we used to hear, due to continuous heavy rain for this many hours the city is flooded, this is because there is no way for the water to drain, so the water gets collected in low lying areas and flood them. To overcome this proper city planning is necessary.
There is another and final type of flood affecting coastal region, that is coastal flood.
These are caused mainly due to high winds, high tides and storm surge that normally occur due to cyclones. In this the sea water is forced to enter the land and floods the coastal region.
Fig. 3. Coastal flooding
Image source: https://www.zurich.com/
You can see the Fig. 3. for coastal flood illustration. Coastal barriers can reduce the effect of the coastal flooding.
I hope now we have a brief idea about the flood, its types and reason for occurrence. The floods can't be avoided, but proper planning can alleviate the effects caused by them.
Stay tuned to know more about other natural disasters!