Super Dikes

A super dike is a high embankment with a wide base and gentle slope. It tends to be larger than a standard dike and designed to be resilient to earthquakes, erosion and breaches, since water is expected to flow more slowly if the dike is overtopped.

Japan began building super dikes in the late 1980s along rivers in Tokyo and Osaka. These dikes are up to 30 times as wide as they are high. They may also be multifunctional, incorporating residential, commercial and public spaces. Since 2011, super dikes in Japan have been reserved for low-lying areas or densely populated, built-up areas in large cities where serious consequences are most likely to occur in a large-scale flood. The super dike concept is relatively new in other parts of the world.

Super Dike: Mixed Residential and Retail
Potential Benefits Potential Challenges
  • Super dikes are designed to be more resistant to breach, erosion and earthquake
  • Multifunctional design is possible>
  • Views of the water are possible from atop the structure
  • Gentle slopes can offer public amenities and access to water
  • Requires more land than regular dikes
  • Like other dike, super dikes:
    • Can be overtopped if not sufficiently high
    • If over-relied upon for flood management, conservative land use and floodproofing measures may not be deemed as important in flood hazard areas, and more intensive development can result in losses in the event of a failure
    • On a river, could constrain the channel.
  • Land acquisition and construction are complex and expensive undertakings
  • Ownership and tenure must be determined for structures on the dike

In BC/Lower Mainland 

In BC, the City of Richmond is integrating super dikes into its long-term flood plan for Lulu Island. The concept involves raising the land on the landward side to the same elevation as the dike crest. The District of Squamish is also looking at the prospect of super dikes in that community.