Measuring the FloodNumerous factors affect stream flow, and the potential for flooding. The most important factors are the amount and type of precipitation, the nature and condition of the drainage basin, and climate. These factors can cause flooding individually or in combination.

Floodplain in FallThe Floodplain

The floodplain is a natural extension of the river channel; a flat, lowland area, which has been carved out by repeated flooding over time. Floodplains are an integral part of a river ecosystem. They are vital to the health of a river, as they filter water - improving water quality, and provide habitats and breeding sites for plants and animals.

From the environmental perspective floods are vital for creating and maintaining floodplains. Such flood waters bring new supplies of seeds, microscopic plants and animals, nutrients and oxygen. Flood waters activate the new generation of plants and animals necessary to sustain a healthy ecosystem in a river valley. Flood waters also increase erosion, which in turn increases changes to the rivers course and can result in the formation of oxbows and lagoons - other vital river habitats.

The Benefits of Flooding

Floodplain wildlife - Blue HeronFloods are natural phenomena; they play a role in the diversity, functionality and productivity of a number of ecosystems. When rivers overflow their banks due to melting snow or torrential rains, floods enrich surrounding land, leaving behind organic material and minerals in the sand, silt, and debris. Ancient Egyptians planned their planting and their lives around the summer flooding of the Nile, which leaves a thin, even coating of black mud along either side when it recedes, leaving the soil so enriched that fertilizer is unnecessary.

Floodplain vegetation and soils serve as water filters, intercepting surface water runoff before it reaches the lake, stream or river. This process aids in the removal of excess nutrients, pollutants and sediments from the water and helps reduce the need for costly cleanups and sediment removal.

For those who live and work near rivers or lakes, flooding is a fact of life. Although we attempt to minimise the effects of flooding, it is impossible to prevent floods altogether. Being prepared for flooding and having emergency plans must therefore be a priority both for residents and for the local officials who are responsible for the safety of their communities.

How to Flood Proof Your Home
Flooded Bench
Learn as much as you can about flooding in your community.

If your house is located in one of the areas mapped under the Flood Damage Reduction Program, you can receive detailed information on flood levels from Environment Canada offices.