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RI Coastal Resources Management Council

...to preserve, protect, develop, and restore coastal resources for all Rhode Islanders

Hurricanes and Coastal Storms

STORMTOOLS

Illustrates and displays storm inundation, with and without sea level rise, for different types of storms that could occur along Rhode Island’s coast line.

CRMC Policy Relating to Coastal Hazards

The Coastal Resources Management Program (CRMP) has developed regulations for reconstruction after "the big one" as well as other severe storms (Section 180. Emergency Assents). More important are the regulations that are designed to minimize the impact of coastal hazards. Policies regulating where to build on a vulnerable property (Section 140. Setbacks), construction of shoreline protection facilities (various sections), and beneficial reuse of dredged materials help to mitigate some of the hazards associated with coastal living. Sea level rise is a hazard that is only indirectly addressed in the CRMP. Erosion setbacks are very effective regulations that protect the homeowner and the public resources. Much of the Rhode Island shoreline is eroding. Erosion rates are calculated by comparing the shoreline location from historic aerial photographs to the most recent shoreline position. Sections of the south shore barriers have erosion rates of more than three feet per year. That is an average rate over time. In reality, the shoreline may erode tens of feet in a single storm, followed by some accretion. In critical erosion areas on barriers, all residential construction with less than six units must be set back 30 times and commercial property 60 times the average annual erosion rate. The farther the house or commercial structure is setback from the shore, the longer it will last. Unfortunately, these regulations were enacted about thirty years ago. The Council may want to consider policy for when the setback is gone and the structure is on the active beach (figure 1).

House pilings in the wave swash

Figure 1. House pilings in the wave swash. Old pilings and ISDS exposed after a storm.

Impacts of storm erosion on ISDS are a potential public health problem (figure 2). CRMC worked with RIDEM to develop regulations for repairs to ISDS in critical erosion areas (ISDS Repair Guidance in Critical Erosion Areas, January 31, 2006).

ISDS exposed by storm surge and waves

Figure 2. ISDS exposed by storm surge and waves.

Shoreline Protection Structures are prohibited along Type 1 shorelines except where they are used to protect historic structures that are listed on the National Register of Historic Places (Section 220). There are several reasons for this prohibition. The structures reflect wave energy, often causing erosion around the sides of the structure and can cause scouring seaward of the structure. In addition, the structures disrupt sediment transport, both by sequestering sediment that would normally erode from a bank or dune to form new beaches (figure 3), and by physically blocking the sand movement along the shoreline (figure 4). Shoreline protection structures often impact lateral public access along the shoreline. In other words, these structures help protect the property where they are built, but often harm adjacent properties. They are a contributing factor in the narrowing and loss of beaches, and they inhibit the public's right to lateral shoreline access (figure 5). Many of the structures that were built prior to the CRMP cannot withstand moderate storms (figure 6).

Sediment that erodes from the headland bluffs forms the beaches

Figure 3. Sediment that erodes from the headland bluffs forms the beaches. The dotted line marks the extent of the slump block before the sediment was transported by waves and currents.

The jetty interrupts the longshore sand transport

Figure 4. The jetty interrupts the longshore sand transport.

Lateral access is limited to low tide

Figure 5. Lateral access is limited to low tide.

Many shoreline protection structures cannot withstand moderate storm energy

Figure 6. Many shoreline protection structures cannot withstand moderate storm energy.

CRMC advocates the beneficial reuse of dredged material. The South Coast Habitat Restoration Project is an example of beneficial reuse that has created wider beaches and has the secondary benefit of providing protection for some coastal properties (figure 7).

Beach with dredged sand shows no erosional scarp

Figure 7. Beach with dredged sand on the left shows no erosional scarp. The beach on the right shows dune scarp and newly exposed ISDS.

Prepare for hurricane season

June 1 marks the official start of the Atlantic hurricane season, and the National Oceanic and Atmospheric Administration (NOAA) predicts an above-normal year with 14-21 named storms (see the NOAA May 24 press release). Of those storms, 6-10 are predicted to become hurricanes, 3-6 of which are expected to be major hurricanes with winds in excess of 111 mph (Category 3-5). The NOAA National Hurricane Center website provides regularly updated hurricane information, including new experimental storm surge maps in tropical cyclone advisories. (See the National Weather Service Hurricane and Tropical Storm Watches, Warnings, Advisories and Outlooks web page for information on the difference between watches and warnings for hurricanes and tropical storms.)

Now that hurricane season is here, it is time to get prepared and stay prepared for these storms.

See links below for more information.

2022 NOAA Hurricane Preparedness Summit
National Oceanic and Atmospheric Administration (NOAA)
Colorado State University

Extended Range Forecast of Atlantic Seasonal Hurricane Activity and Landfall Strike Probability (PDF) from CSU Tropical Weather and Climate Research

"We have decreased our forecast but continue to call for an above-average 2022 Atlantic hurricane season. Sea surface temperatures averaged across the tropical Atlantic are slightly warmer than normal, while subtropical Atlantic sea surface temperatures are cooler than normal. Vertical wind shear anomalies averaged over the past 30 days over the Caribbean and tropical Atlantic are slightly weaker than normal. Current La Niña conditions are likely to persist for the rest of the Atlantic hurricane season. We continue to anticipate an above-normal probability for major hurricanes making landfall along the continental United States coastline and in the Caribbean. As is the case with all hurricane seasons, coastal residents are reminded that it only takes one hurricane making landfall to make it an active season for them. They should prepare the same for every season, regardless of how much activity is predicted."

Landfalling Hurricane Probability Project

Probabilities of tropical storm-force, hurricane-force and major hurricane-force winds occurring at specific locations along the U.S. East and Gulf Coasts within a variety of time periods are listed on the Landfall Probability Web site. The site provides U.S. landfall probabilities for 11 regions and the individual counties along the U.S. coastline from Brownsville, Texas, to Eastport, Maine. Individual state probabilities are also available. The website, available to the public at http://hurricanepredictor.com, is the first publicly accessible Internet tool that adjusts landfall probabilities for regions and counties based on the current climate and its projected effects on the upcoming hurricane season.

Relevant Documents
Informational Links

American Red Cross RI

RI Emergency Management Agency:

National Hurricane Center Resources

Hurricanes: Science and SocietyMajor goals of Hurricanes: Science and Society are to provide foundational science for understanding complex scientific content, inform visitors about current scientific and technological advances, and to help visitors make good decisions prior to and during a hurricane emergency.

Historical Perspective

Quonochauntaug 1954 & 2004

Misquamicut 1954 & 2004

 

Ninigret Pond in 1954 and Dauphin Island AL during Hurricane Katrina 2005

Relevant Sections of the CRMP Dealing with Coastal Hazards

The following lists the relevant sections of the Coastal Resources Management Plan dealing with coastal hazards.

Post Storm Actions:
Section 1.1.14 Emergency Assents

Pre Storm Mitigation:
Section 1.1.9 Setbacks
Section 1.2.2(A) Coastal Beaches
Section 1.2.2(B) Barrier Islands and Spits
Section 1.2.2(D) Coastal Headlands, Bluffs and Cliffs
Section 1.2.2(G) Dunes
Section 1.3.1(G) Construction of Shoreline Protection Facilities.
Section 1.3.1(I) Dredging and Dredged Materials Disposal

Stedman Government Center
Suite 116, 4808 Tower Hill Road, Wakefield, RI 02879-1900
Voice 401-783-3370 • Fax 401-783-2069 • E-Mail cstaff1@crmc.ri.gov

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An Official Rhode Island State Website