1. Definition of Floods
Flood: Overflows of large amounts of water onto land that is normally dry.
Coastal flood: Happens near a coast
River flood: River rises and overflows its banks
Flash flood: takes place suddenly and lasts for a short period of time

2. (reasons for a HIGH surge of water)
Causes of floods
(reasons for a HIGH surge of water)

3. Rainfall
Generally, the more rain there is, the higher the chance of flooding.
Rainfall intensity: rate in which rain falls
Rainfall duration: duration
Rainfall frequency: how heavy the rainfall is
Is there more water if there is increased rainfall intensity, duration and frequency?

4. Snowmelt Surface runoff from melting snow
Increased temperatures result in more melting.
The melted snow (water) will lead to increases in the amount of water in rivers.
Higher temperature > More snow melts > Higher amount of waters in rivers.

5. Failure of man-made structures
Man-made structures like dams and levees are constructed to contain water.
Failure / Breakdown of these structures will lead to an increase amount of water flowing downstream and/or the surrounding area.

6. Cities/areas prone to floods
(additional reasons for flooding)

7. Height of land above sea level
Low levels of land (below sea level) are prone to floods.

8. Proximity to water bodies
Closeness to oceans, seas, lakes, rivers and reservoirs are prone to floods.

9. Permeability of surface cover
Concrete surfaces are impermeable and water is unable to infiltrate into the ground. This increases the chances of floods.

10. Channel (river) capacity
A river with a small capacity that is unable to hold a sudden surge in volume of water (due to too much rain) will be more prone to floods.