The Future is Now

Coastal Rockingham County is particularly vulnerable to coastal flood events when compared to the rest of northern New England. The region experiences frequent inundation of roads and properties from storm events and high astronomical tides. In a recent case, severe coastal flooding occurred in the region on  December 23, 2022 , which rivaled the impacts of  March 3, 2018  and the  Patriot’s Day Storm, April 16, 2007 .

In Governor Sununu’s  letter requesting a presidential disaster declaration , it is noted that Rockingham County sustained $542,175 worth of damage as a result of the storm. 

The Gray ME National Weather Service identified four oceanic and atmospheric conditions that result in coastal flooding. Major coastal flood events in the Gulf of Maine are all about alignment of these conditions.

Twice per 24-hour cycle, the tide rises to the highest level it can reach. The Storm needs to peak at high tide.

Storm Surge is the rise in sea level that occurs during a storm. Wind from storms pushes sea water onto shore to create the surge. The storm peak, high tide and surge need to align for a major flood event.

Wave Run-Up measures the height that waves can reach up an on-shore barrier such as a bank, seawall, or revetment. For a major flood event the largest waves need to occur with the storm peak and high tide.

High Astronomical Tide is the tide level that occurs during full or new moon cycles. These are often referred to as King tides or spring tides. For major coastal flooding the peak storm conditions need to occur around the HAT.

 For major coastal flooding events to occur, these conditions must align.

Yes!

At the same time that the storm peaked, high tide was already naturally occurring within the 24-hour cycle.

Yes!

Data from the Portland and Hampton tide gauges measured a nearly three foot storm surge.

Yes!

Buoy data shows that the highest waves occurred at our around peak storm conditions and high tide.

Yes!

If the same storm hit on Dec 14th, the water level at Hampton would of been around 10.2 feet, barely above action stage.

This satellite loop shows the evolution of this powerful storm system as two areas of low pressure develop into an intense cyclone and moves into the Great Lakes region.  The storm rapidly intensified with a central pressure of 970mb by 7 PM on the evening of December 23rd while a strong area of high pressure remained anchored over eastern Canada. The stark contrast in pressure resulted in the very strong and gusty southeast to east winds across the region on December 23rd.

With the track of this storm west of the region, this was not a true Nor'easter; demonstrating that the New Hampshire Seacoast is very vulnerable to this wind direction as well. In recent years, we have had several damaging storms from this wind direction, which may be due to the very warm water temperatures in the Gulf of Maine over the last several years. In addition, tropical systems and hurricanes that track into central New England often bring strong east or southeast wind. 

The majority of notable coastal flood storms are usually large Nor’easters.

This storm was unique due to the quick hitting westward track it took and the southeast wind direction. 

The longevity of a constant wind fetch was favorable for large, near-shore waves.

The December 23rd storm, combined with high astronomical tides, resulted in the second highest tide in recent history at Seavey Island and the fourth highest at Portland Harbor, ME.

The Seavey Island tide gauge along the Maine/New Hampshire border showing the peak tide at 12.5 feet (MLLW) at high tide, a full foot above flood stage.

The astronomical tide at Hampton Harbor was 10.3 feet at 10:30 am. The storm tide reached 13.2 feet (datum MLLW) due to the accompanying 2.9 foot storm surge. Flood stage in Hampton, NH is 11.0 feet.

 Summary of High Tide Flooding by the Hampton NH Tide Gauge 2013-2020– NH Department of Environmental Services. 

Sections of Route 101 west of the beach were closed due to flooding in the vicinity of Drakeside Road (left). Drakeside Road itself was inundated with shoulder washout observed as the tide receded.

Winnacunet Road experienced flooding west of Ocean Boulevard. Water is estimated to have been 1.5 to 2 feet deep.

Cusak Road flooded 90 minutes prior to high tide.

Residences on Glade Path (left) and Island Path were cut off from rest of the community as these dead-end roads were flooded, preventing safe travel to the connecting road network.

During this event, many neighborhoods and streets that are familiar with relatively common sunny day flooding experienced significant flooding. Areas west of Ashworth Road and Brown Avenue experienced extensive flooding. The Hampton Police Station was reportedly surrounded by water at high tide.

The road was inundated with at least 6 inches of water. The photo on the right from an emergency vehicle shows rocks and debris were scattered along the road.

The historic fish houses took a direct hit, with at least one of the structures being dislodged from its foundation.

Some of the more significant flooding occurred in the vicinity of Rye Harbor. On Ocean Boulevard (NH 1A) near Harbor Road, the marsh area spilled onto NH 1A (left). At the Harbor entrance northward to Rye Harbor State Park, NH 1A was inundated by an estimated 2 to 3 feet in some areas. Large stones and debris Made NH 1A impassible and required plowing just north of the harbor.  The shale piles across from Ray's Seafood restaurant on Ocean Blvd were breached, as were multiple locations to the north including Washington Road.

Harbor Road (east of NH 1A) experienced significant pavement damage as the storm tide compromised the pavement and substructure.  This is primarily a residential road serving oceanfront property.

North of the Rye Harbor entrance, approaching Rye Harbor State Park, significant flooding occurred. Flood water levels likely approach three feet deep and moved large stones and debris covering NH 1A. This made it impassible for several hours.

Wallis Road at Appledore Road was submerged under more than 1.5 feet of water. The marsh area flooded and cut off access to residents on Appledore Ave. This was noted by local residents as the "most extensive flooding" they have ever seen in the area.

In addition, NH 1A and Wallis Rd (at Pirate's Cove) experienced wave run up. The waves overtopped the beach access area, sending additional floodwater onto NH 1A and Wallis Road.

Marsh Road near Parsons and Brackett were impassible in the hours approaching high tide.

As high tide approached on December 23rd, flood waters overtopped NH 1B at Sanders Poynt, one of two access points for the island of approximately 1,000 residents.

During the December 23rd storm, both island access points were cut off by flooding during high tide. At the north access way, flood water overtopped the causeway east of Goat Island (right) and the Kittery Point Yacht Club.

The causeway was damaged in this area with undermining of the pavement shoulders reported. This photo is looking west towards Portsmouth and shows Goat Island and the Kittery Point Yacht Club.

Mechanic Street was closed due to flooding from the intersection of Peirce Island Road past Geno's Chowder and Sandwich Shop.  

Also flooded was Walden Street, South Mill Street, Pickering Avenue, Partridge Street, Parrott Avenue, New Castle Avenue, Ceres Street, Lafayette Road, Leary Field, and Haven Park.

Site #4 of the STCVA is along NH 1B New Castle Avenue between Marcy Street and the bridge/causeway to Shapleigh Island and Goat Island. At 4.0 feet of sea level rise, sections of this roadway are projected to be inundated, potentially isolating approximately 50 residences in Portsmouth as well as cutting of one of two access ways to New Castle. 

In New Castle, the causeway between Goat and New Castle Islands is projected to be overtopped. The December 23rd storm tide overtopped the causeway between New Castle Island and Goat Island, cutting off access to the mainland for a period of time.

Site #11 of the STCVA is along Ocean Boulevard and Wallis Road. It's projected to see daily flooding from 4.0 feet of sea level rise.  The December 23rd storm brought an estimated 2 feet of water across Wallis Road between Ocean Boulevard and Appledore Avenue. In addition, wave run-up overtopped the beach access point at the end of Wallis Road.

Site #13 of the STCVA is along Ocean Boulevard near Rye Harbor. This area is projected to see daily flooding from high tides under a 4.0 sea level rise scenario. The December 23rd storm brought severe flooding to this stretch of roadway. At the Harbor entrance northward to Rye Harbor State Park, NH 1A was inundated by an estimated 2 to 3 feet in some areas. Large stones and debris Made NH-1A impassible and required plowing just north of the Harbor. The shale piles across from Rays Seafood restaurant on Ocean Blvd were breached.

Site #17 of the STCVA is along Ocean Boulevard near Winnacunnet Road in Hampton. 4.0 feet of sea level rise is expected to overflow the marsh and inundate portions of the areas daily.  The December 23rd storm did just that, with upwards of 18 inches of seawater covering large portions of the area cutting off access to homes and businesses.

As impactful as the December 23rd storm and flooding event was, New Hampshire and eastern New England narrowly missed a much more impactful storm just three months earlier.  

On September 24, Hurricane Fiona passed roughly 350 miles east of the New Hampshire Seacoast making landfall in eastern Nova Scotia. As Fiona moved north into the Canadian Atlantic, warmer than normal ocean water helped maintain Fiona’s strength. As is often the case in northern latitudes, the storm interacted with a trough in the jet stream, resulting in an expansive storm that shattered records for the lowest barometric pressure ever to be recorded in Canada.

Winds gusted up to 110 MPH and caused snapped utility poles, uprooted trees, and structural damage. A storm surge up to six feet, combined with wave heights of eight to ten feet, swept homes off the rocky shorelines of Nova Scotia and Newfoundland.  The storm caused at least 3 fatalities and upwards of $700 million of insured losses to the local economy.

Fiona is a wake-up call to the residents of the New Hampshire Seacoast that we are vulnerable to the impacts of tropical storms and hurricanes. 

The impacts of a storm like Fiona on the New Hampshire Seacoast would be extreme.  If landfall occurred in southern New England with a corresponding high tide, a storm surge of up to 4 to 6 feet topped by wave heights of 8 to 10 feet would likely compromise the shale piles and sea walls on NH 1A in multiple locations.

Roadway infrastructure on NH 1A and adjacent local roads would likely be impassable with pavement failure and wash outs.

Flooding would likely extend inland through marsh areas, isolating neighborhoods and inundating dozens of structures from Seabrook to Portsmouth. The most vulnerable neighborhoods in Hampton could see three to six feet of flooding.

As a region, we have made significant investment in planning for sea level rise and other climate related impacts. This is important work that needs to continue. However, in our efforts to plan for the future, we cannot continue to look past the immediate threat of extreme weather.  The time is now to invest in infrastructure improvements to mitigate the costly impacts of a Fiona like storm. The cost of inaction will greatly outweigh the investment in our communities today.