Portland's annual storm tide reaches approximately 11ft 7in, just below the city's 12ft flood stage. Portland experiences these storm surge heights:
25-100 YEAR 4-4.7FT
5-10 YEAR 3FT
ANNUAL 2FT
These storm surge statistics are based on more than a century of water-level observations collected at Portland Harbor and analyzed by the Maine Geological Survey. Together, these records provide a benchmark for understanding how sea level rise will influence future storm tides and coastal flooding along Portland area shorelines.
The following video shows typical conditions during an annual winter storm at the Diamond Cove pier. The predicted tide was 10ft and the recorded storm surge was 2ft 1in, producing a storm tide around 12ft. As sea levels rise, annual storms like this will occur on top of higher baseline water levels, increasing the frequency and extent of coastal flooding.
The following video shows conditions during a storm tide of 12ft and a storm surge of 2-3ft. Water levels of this magnitude are typically associated with storms that occur approximately every five years. By 2030, the projected 8in increase in sea level will cause annual winter storms to produce flooding impacts more comparable to the conditions shown here.
Interested in taking a deeper dive into how projected sea level rise is expected to influence water levels on Great Diamond Island? Tap either button below to learn more.
