Aerial View of Floodplain

Most flooding occurs when the volume of water in a river or stream exceeds the capacity of the channel. Flooding also takes place along lake and coastal shorelines, when higher than normal water levels engulf low-lying areas.

Natural flooding of rivers revitalises the habitats of many plants and animals and enriches soils for planting. But floods can cause destruction and harm to those who live in their paths.

Flooding is a common phenomenon in Canada, resulting from an increase in stream-flow beyond the point where the normal stream channel can contain the water. When water overspills riverbanks, it spreads out along the adjoining floodplain. Flood-waters may occupy the floodplain for a matter of hours, as in the case of flash floods, or for up to two months, as sometimes occurs during the spring snowmelt runoff period.

Learn about flooding in your watershed

Adapted from Environment Canada's Freshwater website and the National Geographic's Flood and Dams.