Falmouth

Contour lines can help visualize this steep topography. Here, orange lines represent elevations between 0 and 10-feet above sea level (in 2-foot increments).

The current highest astronomical tide (HAT) is displayed in red. HAT is the highest tide that can occur under average weather conditions, and is about 1.9 feet higher than Mean High Water in Casco Bay (the average height of daily high water). It provides a useful baseline for assessing potential sea level rise.

The State of Maine estimated sea level rise scenarios on top of the HAT. The State asks communities to commit to managing 1.5 ft of sea level rise by 2050 and 4.0 ft by 2100 (relative to a year-2000 baseline).

The map at right shows the area expected to be inundated with 1.5 feet of sea level rise. Note that extreme storm surges (the rise in water level from storm winds piling water up at the coast) can reach around 3-4 feet above sea level.

The amount that sea level will rise depends in part on what we do to curb greenhouse gas emissions, communities should account for multiple future sea level rise scenarios. In this visualization, 3.9 feet of sea level rise encroaches farther inland. The State asks that communities be prepared to manage for this level of water, especially for high priority infrastructure, ecosystems and when people are at risk.

The Federal Emergency Management Agency (FEMA) maps the area likely to be flooded by severe storms that have a 1% chance of occurring within a given year, under current conditions. Over thirty years, there is a 26% chance that a storm of this severity will occur at least once, so it's important to plan for.

Together, these predictions (FEMA "100-year" flood risk and HAT + 3.9 feet of sea level rise) provide a look into how flooding could impact our coastlines, habitat, infrastructure, and people within this century. FEMA does not factor climate projections into their flooding maps, so combining with sea level rise maps show a more complete picture of impacts.

Some organisms, like molluscan shellfish (habitat of which is mapped at right), are important culturally as well as economically and environmentally. 

Various bird species require appropriate tidal habitats; rising sea levels and increased flooding may eliminate some of this habitat. Highlighted here are tidal wading bird habitats and seabird nesting islands. 

While all habitat is valuable, Falmouth has areas, shown in green, home to particularly vulnerable wildlife. Relevant species include roseate tern and least bitern. 

Because habitat can be disrupted by inland or coastal flooding, it may be helpful to provide buffers around habitat areas. This provides the opportunity for plants and animals to shift into new locations without the threat of encroaching development. 

Fortunately, a number of spaces within the Town's border are already protected for conservation or open space, mapped at right. 

The Nature Conservancy developed an analysis of culverts at risk of overtopping in a flood. Several culverts in Falmouth are assessed at high or medium risk for overtopping. These culverts should be examined and potentially improved. 

Also at risk are elements of the area's transportation network. Shown here are roads and transportation routes, as well as the previously flood hazard and sea level rise layers. 

Residents and emergency services should be aware of areas and road segments where access might become limited with flooding; this could result in safety hazards as well as travel impediments to private and public transit. These road segments are highlighted in yellow. 

Several buildings in Falmouth intersect with these estimated flooding areas as well. These are highlighted in red on the visual at right. These should also be assessed for safety, stability, and resilience in the event of flooding, storm surge, or sea level rise. 

In Falmouth there are significant areas of least bittern habitat that is not conserved and could be threatened by future development.

Coastal defenses and infrastructure along Andrews Avenue to Mackworth Island and the Martins Point Bride on Route 1 to Portland are at risk of overtopping. This infrastructure is also at risk of future flooding and could sustain impacts that cut off travel.

The potential for flooding, and any impact on emergency services and travel, should also be considered at at the the I-295 bridge over the Presumpscot River.

Falmouth has three at risk dams that should be assessed for longevity, resilience, or maintenance if necessary. Potentially undersized culverts identified by the Nature Conservancy should also be assessed, and improved if necessary.

The Town Landing currently floods in high water and has sustained impacts from storms. The Town is studying opportunities for improving vulnerability. The riprap and coastal defenses here are shown to be at risk of overtopping.