Flooding can occur due to natural processes or human activity. The most common types of flooding are listed below.

River flooding, or fluvial flooding, occurs when a river's flow exceeds its capacity and floods the area around it.  

River Flooding Image

Sewer flooding can occur when the sewer system does not have enough capacity to take water entering the system as a result of heavy rainfall or river or highway flooding.  


Groundwater flooding occurs when rainfall causes the water that is naturally stored underground to rise to the surface, flooding low-lying areas.

Groundwater Flooding

Surface water flooding happens when there is heavy rainfall on ground that is already saturated, or on surfaces where drainage is poor.

Surface Water Flooding Image

Weather and tidal conditions can increase sea levels.  This can lead to coastal overtopping and flooding from high tides and storm surges. The frequency and severity of this type of flooding is predicted to rise. 

Coastal Flooding Image