Hurricanes and Coastal Storms
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).
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).
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).
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.
Figure 4. The jetty interrupts the longshore sand transport.
Figure 5. Lateral access is limited to low tide.
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).
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.
 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 180. Emergency Assents
Pre Storm Mitigation:
Section 140. Setbacks
Section 210.1. Coastal Beaches
Section 210.2. Barrier Islands and Spits
Section 210.4. Coastal Headlands, Bluffs and Cliffs
Section 210.7. Dunes
Section 300.7. Construction of Shoreline Protection Facilities.
Section 300.9. Dredging and Dredged Materials Disposal
Prepare for Hurricane Season NOW!
Hurricane Season Outlook: In its initial outlook for the 2009 Atlantic hurricane season, which runs from June through November, NOAA’s National Weather Service Climate Prediction Center calls for a 50 percent probability of a near-normal season, a 25 percent probability of an above-normal season and a 25 percent probability of a below-normal season. Global weather patterns are imposing a greater uncertainty in the 2009 hurricane season outlook than in recent years. Forecasters say there is a 70 percent chance of having 9 to 14 named storms, of which 4 to 7 could become hurricanes, including 1 to 3 major hurricanes (Category 3, 4 or 5).
On average, the north Atlantic hurricane season produces 11 named storms, with six becoming hurricanes, including two major hurricanes. In 2005, the Atlantic hurricane season contained a record 28 storms, including 15 hurricanes. Seven of these hurricanes were considered "major," of which a record four hit the United States. "Although NOAA is not forecasting a repeat of last year's season, the potential for hurricanes striking the U.S. is high," added Lautenbacher.
Warmer ocean water combined with lower wind shear, weaker easterly trade winds, and a more favorable wind pattern in the mid-levels of the atmosphere are the factors that collectively will favor the development of storms in greater numbers and to greater intensity. Warm water is the energy source for storms while favorable wind patterns limit the wind shear that can tear apart a storm's building cloud structure.
This confluence of conditions in the ocean and atmosphere is strongly related to a climate pattern known as the multi-decadal signal, which has been in place since 1995. Since then, nine of the last 11 hurricane seasons have been above normal, with only two below-normal seasons during the El Niño years of 1997 and 2002. With neutral El Niño/Southern Oscillation (ENSO) conditions expected across the equatorial Pacific during the next three to six months, the NOAA Climate Prediction Center scientists say that neither El Niño nor La Niña likely will be a factor in this year's hurricane season.
Relevant Documents
Hurricane Resource Guide (PDF) from Get Hurricane Ready RI
RI CRMC Hurricane Preparedness Guide (PDF)
RI State Hazard Mitigation Plan (PDF)
Informational Links
RI Emergency Management Agency:
National Oceanographic and Atmospheric Administration
State of Rhode Island Web Site
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