Question

mention the element at risk during flood

Answer 1

soil, flora, faunna, human life

Answer 2

 

How do floods occur?

At least once a year the plains around large rivers are flooded. This is due to the amountof water that rivers bring with them, because of heavy rainfall or melting snow in the mountainous regions. Thunderstorms can cause flash floods, in which small rivers can swell quickly and carry up to ten times the normal amount of water.

Rivers that flow slowly carry water, sand and silt. They build up their own beds, making them higher than the land around them. The Huang He, or Yellow River,  in China and the Mississippi in North America are examples for such rivers. Flooding here builds upslowly but causes more damage because more land is affected.

Coastal regions can also be affected by flooding. After earthquakes on the ocean floor tsunamis can bring up to 15-metre high waves and flood the coast many miles inland.  In 2004, a devastating tsunami in the Indian Ocean killed over 250,000 people in Indonesia, Sri Lanka, Thailand and other countries.

Tropical storms, cyclones and hurricanesalso lead to flooding. Hurricane Katrinacaused a massive flooding of the whole Mississippi Delta in 2004. Most of New Orleans had to be evacuated because of widespread flooding.