Flooding

Flooding is the most common natural hazard on the planet. Between 1995 and 2015 floods made up almost half of all weather-related disasters, affecting more than two billion people. A flood happens whenever water arrives faster than the land or a river channel can carry it away, so the river spills over its banks and drowns the floodplain. The causes are partly natural, such as heavy rain and steep slopes, and partly human, such as cutting down forests and paving over the ground.

In this lesson you will learn the physical and human causes of flooding, read a storm hydrograph to see how quickly a river responds to rain, and follow the Environmental Management chain of cause, impact and management. The deadly 2010 Pakistan floods provide a named example, and you will also see why, despite the danger, flooding brings real opportunities such as the fertile silt that has fed civilisations for thousands of years.