What are floods anyway? Well, floods are actually an overflow of water that usually submerges DRY LAND. It may result from the volume of water within a body of water like a river or lake. There are several causes for floods to occur. Basically there are human and natural causes. We shall explain more about the causes.

Let's start with the natural causes first...

1. Storm surges - At coastal areas, strong winds raise the waves in the ocean to an exceptionally high level. When they crash onto the coast, they may flood the land.
2. Excessive rain - Places with tropical Monsoon climate like India will have heavy rain seasons a.k.a wet seasons. Flooding will occur when the river channel in these countries are not able to contain or hold the excess rainwater.
3. Melting snow - This factor is easy to understand. When the season change from winter to spring, the snow will melt and releases massive amounts of water into rivers.
4. Global atmospheric processes (El Nino and La Nina) - This factor is difficult to understand. The other PG group doing global warming had a hard time understanding what's this is about. El Nino is the abnormal warming of water surface at the southeastern part(SE) of the Pacific Ocean(PO). What happens? Ocean heats up and cause heavy rain over the SE part of PO. Then how bout La Nina? Well, it usually follows after El Nino.La Nina is almost the opposite of El Nino, heating up the SW part of PO. Same thing follows. Ocean heats up and heavy rain occurs over Australia and Indonesia.
5. Movements of the Earth's surfaces - Remember the Indian Ocean tsunami? What am i thinking? of course you remember! Floods are actually caused by earthquakes too. Soil loosens, make river shallower, and then flood occurs. Earthquake trigger off tsunamis which can flood settlements too.