For a simple and scientific explanation of floods and different types of floods, visit this link. The language is simple and the concepts are clearly explained in this site. See the diagrams to understand how the landscape changes when floods occur.
Causes of floods
To understand how floods are caused, the extent to which they can be considered as "acts of God" and how the activities of man can make floods more or less severe, read this comprehensive guide here.
It is written mainly for insurance companies, builders and other professionals and talks mostly of flooding in UK. But it is very informative as the basic facts remain the same- the change in landscape, land use, how the size of the river basin and the flood plain affects the severity of floods, and how we can prepare for floods in a flood prone area.
1998: A year of floods
One of the nature's most turbulent years was 1998. Floods wreaked havoc in North America, South America, Asia and Europe. Though the El Nino and La Nina were thought to be responsible for these floods, scientists have now found out that these factors combined with global warming caused by pollution and made the disasters more severe.
Deforestation and global warming are cited as two of the main man-made causes that led to such a disastrous year with loss of lives and huge damage. Read these reports from BBC network on some of the worst floods and the devastating effect of Hurricane Mitch - all testimonies to the result of human activity interacting with natural phenomena.
Are man-made floods possible?
A debate around the world is that nature is to blame for natural hazards while one section says that man causes or triggers these hazards by deforestation and pollution. In China, a flood affected the lives of 250 million people and caused large scale devastation and the El Nino was cited as the main cause.
But after some analysis, it has been found that it was caused by large scale deforestation leading to loose soil and therefore huge floods. Read this article to know more about this debate.
How are floods caused by man? How do man-made changes in a river basin affect floods? In Washington, floods are caused by man-made actions. The rapid urbanization of Washington has led to more concrete surfaces that seal the surface and do not allow water to seep in.
Dikes can help contain the water but they also cut off the river from the floodplain. The floodplain helps to retain some of the floodwater but cutting the river off from it means that this natural storage is gone. The consequent pressure on the environment leads to such disasters. Download this report to find out more.