Friday, 22 January 2016

A Bit of Science About Floods

Kuala Lumpur has been hit by rain almost every day recently and every time that happens people wonder if there will be a flood somewhere, followed by traffic jams and other calamities. What is a flood? A flood is an imbalance in a hydrological system. This means there is more water flowing through the hydrological system than it can carry. 

What causes floods?

Very heavy rain 
Over-saturated soil, when the ground can't hold anymore water 
High levels of water in a river, stream or reservoir caused by unusually large amounts of rain 
Construction, urbanisation or lots of buildings and parking lots

In cold countries floods can also be caused by run-off from deep snow cover, frozen soil and ice jams in rivers.

There are two basic types of floods. In a normal river flood, water slowly rises and spills over the edges of a river. However, flash floods are more dangerous and can cause loss of lives.

What is a flash flood?

A flash flood is sudden flooding that occurs when floodwaters rise rapidly with no warning within several hours of an intense rain. It usually occurs when a wall of water quickly sweeps over an area after intense rainfall from slow moving thunderstorms. In narrow waterways floodwaters flow faster than on flatter ground and can be destructive. 

How much water makes a car float?

People often underestimate the power of water. Did you know that it takes only 18 inches of water to float a vehicle? It takes two feet of flowing water to turn vehicles into dangerous boats. So don’t drive through flooded roads. Six inches of fast moving flood water can knock you down. 

Cities can be flooded by an amount of rainfall that would have had no impact in a rural area because there are less trees, grass, roots and soil to soak up and hold water in. City-dwellers, be extra careful because the concrete jungle is not always made for heavy rain and floods!

Shared by Melissa
Guest Blogger

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