NHC completed a study for City of Vancouver to identify and quantify the assets at risk of damage as a result of sea level rise-induced coastal flooding. The project comprised a hazard analysis with accompanying preparation of hazard mapping, and a high level vulnerability assessment followed by a consequence assessment. The hazard assessment formed the main technical component of the study.

The ocean modelling used a detailed joint probability analysis that analyzed the actual probability of high tide, storm surge, wave and wind set-up occurring simultaneously to estimate different return period flood levels for present and future ocean level conditions. Overland flooding associated with five scenarios was modeled using TELEMAC2D, and flood depths and extents were mapped spatially using ArcGIS. The results informed the update of the City’s Flood Construction Levels (FCLs).

The corresponding vulnerability of areas prone to flooding was assessed, including SWMM modelling of the False Creek stormwater system to assess infrastructure impacts resulting from a 25-year rainfall event plus sea level rise. Using the Hazus-MH tool, the consequences of present and future flooding in terms of building damage and dollar losses were identified.

In the second phase of the project, which currently is in progress, NHC is part of a team that is assessing mitigation options – both structural and planning tools – for minimizing the hazard and/or exposure of inhabitants, property and infrastructure.