Flood – What is at Risk?

The flood hazard areas of BC’s Lower Mainland are home to an estimated 350,000 people. Flood hazard areas include homes, significant critical infrastructure and lifeline services, agriculture and other industries, diverse cultural and social assets — as well as rich natural ecosystems.

Depending on the size of a flood, losses can be serious, even devastating. Losses can result from flood-damaged properties and infrastructure, the displacement of people and business and service disruption and other impacts.

Continued development and population growth in flood-prone areas, combined with the increased likelihood and extent of flooding under climate change, mean that these risks — and the associated losses — are expected to keep growing.

What Does It Mean to Reduce Flood Risk?

Flood risk in a given area is based on the likelihood of a flood and the consequences of that flood.

Flood risk is based on the likelihood of a given flood and the consequences of that flood.

Consequences are based on the:

  • Flood Hazard – location and characteristics of a flood
  • Exposure – people and assets reached by the flood, and
  • Vulnerability – characteristics of a community or an asset that make damages flood more likely, including physical or socio-economic characteristics.

Reducing flood risk means reducing the consequences through:

  • Reducing the flood hazard (e.g., building a barrier to block floodwaters)
  • Reducing exposure to the flood hazard (e.g., locating homes on higher ground)
  • Reducing vulnerability to flood damage (e.g., using building materials that are waterproof, or educating the community on emergency response)

Approaches to Reducing Flood Risk

There are two broad approaches to reducing flood risk: non-structural and structural.

  • Non-structural measures, such as managing land use in flood hazard areas or emergency planning, aim to reduce damages caused by exposure or vulnerability to flood hazards.
  • Structural measures, such as building infrastructure or diversion works, are aimed at controlling the movement of water in rivers or coastal areas to reduce flood hazards.

Combining these measures may be more effective than relying on just one approach.

The approaches described below focus on riverine and coastal flooding. Other types of flooding may require different approaches (such as urban flooding when precipitation overwhelms stormwater infrastructure or drainage systems).

Land Use & Development

Appropriate land use planning and regulation, or floodplain management, can provide very effective non-structural ways to reduce flood risk. The primary approaches are to direct development and infrastructure outside of flood hazard areas and to make buildings, their contents and other structures less vulnerable to flood damage.

Land Use & Development


Infrastructure & Works

Flood protection infrastructure and related works are structural measures designed to help control floodwaters and keep them away from communities, people diverse cultural and social assets. Many communities have historically constructed and relied on these works to protect them from floods.


Setback Dikes

Super Dikes

Sea Barriers

Water Diversion


Beach Nourishment


Natural Shorelines

Sediment Removal

Emergency Management

The Government of British Columbia follows a four-pillar approach to emergency management: mitigation/prevention (aka. risk reduction), preparedness, response and recovery.