Publish and Present
The risk of ocean-driven flooding in the vicinity of coastal infrastructure is increasing rapidly as sea levels rise. To facilitate future planning efforts such as port site selection, computer modelling can be performed to determine inundation severity resulting from sea level rise, storm surge, extreme wind waves, and tsunamis.
Vulnerability assessments of infrastructure in 14 coastal communities in British Columbia, Canada found that some communities will experience significantly shallower tsunami waves or were more sheltered from storm surge and wind wave effects than immediately adjacent shorelines, suggesting that relatively minor changes to a future port or marine terminal’s intended location could have a major impact on the potential level of damage resulting from an extreme ocean-driven event. Additionally, naturally-occurring sea formations such as coral reefs may mitigate the risks associated with these extreme events.
The modelling was performed using MIKE 21©, a hydrodynamic modelling software that simulates flows, waves, sediment transport, and ecology in coastal areas. Models incorporated local and regional bathymetric and topographic survey data and were calibrated based on records of recent tsunami, storm surge, and flooding events.
The vulnerability review considered two flooding scenarios at 2100 sea levels for each community. The first scenario considered three earthquake-induced tsunami events corresponding to a 2,475-year return period. The second scenario considered a joint occurrence of storm surge and extreme wind waves corresponding to a 200-year return period. A combined occurrence of these events with high tide was also simulated as it was considered potentially catastrophic.
The two flooding scenarios were displayed over aerial photographs of each community, indicating that critical infrastructure is potentially at risk and that key defensive structures such as seawalls are likely inadequate under future sea-level scenarios. These flood maps can also be used for high-level planning initiatives such as site selection and infrastructure vulnerability assessments.