Causes of floods Flashcards
What is rainfall?
Rainfall is droplets of water that fall to the ground
What is rainfall intensity?
The rate at which rain falls (mm/h)
How do we calculate rainfall intensity?
The total amount of rainwater (mm) divided by the duration of the rainfall (h)
What is rainfall duration?
It is the length of time of the rain event
What is rainfall frequency?
It is the probability of occurrence of a certain amount of rain falling within a certain period of time.
What is snowmelt?
Snowmelt is surface runoff that results from melting snow
What causes snowmelt?
It is caused by a change in temperature in temperate countries. During winter ice and snow form on mountains but during spring, the temperature rises and causes the ice and snow to melt, leading to surface runoff. It can also be caused by a volcanic eruption.
How does snowmelt cause river floods?
It flows over the land into rivers and increases the volume of water in the river which causes the river to overflow its banks and flood the surrounding area
What is a Storm Surge?
Strong winds that bring large waves which cause water levels to rise and cause coastal floods.
What is a dam?
A barrier built across a river to retain and store water.
