Managing Flooding Risk in Response to Sea Level Rise

Anticipating the effects of sea level rise on existing and planned infrastructure at ports is critical because of the magnitude of the investments and permanence of structures. The City of Olympia has begun the process of determining the effects of future sea level rise and planning for mitigating potential damage to the area encompassing the City's downtown and Port of Olympia property. A recently completed phase of a study undertaken by the City identified areas requiring protection to prevent inundation in a 0.01 chance combination of rainfall runoff, tide, and wave storm for various levels of sea rise. The height of flood barriers necessary to protect the areas in those cases was calculated and outfalls requiring backflow control were identified. The analysis was guided by criteria for protecting critical transportation corridors and critical facilities. A range of appropriate flood barriers was recommended for each area requiring protection, and modifications to existing infrastructure were identified for controlling flooding initially. The study developed a list of recommendations specific to the study area regarding what activities should be done soon, and the point in the sea level rise amount at which other modifications should be undertaken.