The Atlantic and the Pacific: you don’t have to be from the Seacoast to know that they’re different—very different. For example, the Pacific is the largest ocean in the world and is up to two times deeper than the Atlantic Ocean in some places. When comparing oceans, these differences are pretty fundamental. So when Federal Emergency Management Administration issued its flood maps for Massachusetts relying on wave models for the Pacific Ocean, it ruffled a few feathers. Luckily, FEMA has delayed issuing its flood maps for New Hampshire, and hopefully, the negative response FEMA has received, will cause it to rethink its flood maps for the Granite State.
FEMA’s flood maps designate “special flood hazard areas,” which are areas that fall within a “100- year boundary.” The “100-year flood boundary” is the area in which there is at least a 1% chance of a flood in a given year. The flood maps are used in various municipalities to establish “Flood Plain Districts,” often relying on FEMA’s designation of “special flood hazard areas.” These “Flood Plain Districts” often impose special zoning regulations for the construction of new structures, improvements of pre-existing structures, and/or altering terrain within the Flood Plain Districts. The flood maps are also used by insurers to determine flood insurance rates and by lenders to determine what properties will require flood insurance as a condition of financing.
This year, FEMA released its flood map for Massachusetts utilizing the “Direct Integration Method” (“DIM”), which uses wave data tailored to the Pacific Ocean, not the Atlantic. Previously, FEMA has stated that the DIM is appropriate for the East Coast and the Gulf of Mexico. The science behind this statement, however, has been questioned.
Aside from the dimensional differences between the two oceans, the waves in the Atlantic and the Pacific do not act in a similar fashion. Waves off of the Pacific Coast are large, slow moving, and occur at a low frequency. Waves on the Atlantic are smaller, faster, and occur at a higher frequency. The West Coast is also straighter with less offshore islands and shoals when compared to the East Coast. The result: waves on the West Coast, under normal circumstances, come much further ashore than waves on the East Coast and can cause flooding under normal circumstances. East Coast flooding, on the other hand, is often the result of special events such as storm surges—not normal wave patterns.
When FEMA applied the Pacific-centric DIM to create the Massachusetts flood maps, the result designated properties as “special flood hazard areas” that have historically been beyond flood-risk. This designation ultimately causes current and prospective home owners to be subject to higher flood-insurance premiums and special zoning ordinances.
When the new FEMA flood maps for Massachusetts were released, members of the Congressional delegations, Bay State legislators representing affected communities, and UMass Dartmouth scientists quickly mobilized to stay their implementation. Challengers claimed that FEMA had “cut corners” in conducting the methodologies necessary to generate the flood maps. They also claimed that a process called “numerical modeling” should have been utilized, which is exact and site specific, but also more time consuming. Most importantly, the Town of Rockport, Massachusetts filed an appeal with FEMA providing specific data and studies to back its allegations that FEMA’s flood maps were inaccurate.
When faced with the Rockport appeal, FEMA delayed the implementation of the flood maps. In granting the appeal, FEMA stated that “the engineering analysis data submitted in support of the appeal provides evidence that the alternate method for determining wave setup provides a scientifically correct estimate of the Base Flood Elevations for [Rockport].”
As stated above, FEMA has yet to release its New Hampshire flood maps, and they have been reportedly delayed. The same reasons which make the DIM inappropriate for Massachusetts apply to the Granite State. The Granite State coastline is protected, in part, by the Isles of Shoals, is rocky, non-linear, and is infrequently subject to thirty-foot waves. Although bad for surfers, these characteristics make flooding on the coast less likely, absent a storm-surge or other uncommon circumstances. Hopefully, the Town of Rockport’s appeal will make FEMA rethink any proposed flood maps for New Hampshire prior to their release. However, in the event that FEMA does not, there is now administrative precedent to challenge the flood maps.
For more information, please contact Attorneys Eric Maher or Michael Donahue at 778-0686, or you can contact the author by email at email@example.com .