5.2 COASTAL EROSION & SEA LEVEL RISE 5.2 - 1 SECTION 5.2 COASTAL EROSION & SEA LEVEL RISE 5.2.1 HAZARD DESCRIPTION COASTAL EROSION Erosion and flooding are the primary coastal hazards that lead to the loss of lives or damage to property and infrastructure in developed coastal areas. Coastal storms are an intricate combination of events that impact a coastal area. A coastal storm can occur any time of the year and at varying levels of severity. One of the greatest threats from a coastal storm is coastal flooding caused by storm surge. Coastal flooding is the inundation of land areas along the oceanic coast and estuarine shoreline by seawaters over and above normal tidal action. Many natural factors affect erosion of the shoreline, including shore and nearshore morphology, shoreline orientation, and the response of these factors to storm frequency and sea level rise. Coastal shorelines change constantly in response to wind, waves, tides, sea-level fluctuation, seasonal and climatic variations, human alteration, and other factors that influence the movement of sand and material within a shoreline system. Unsafe tidal conditions, as a result of high winds, heavy surf, erosion, and fog are ordinary coastal hazard phenomena. Some or all of these processes can occur during a coastal storm, resulting in an often-detrimental impact on the surrounding coastline. Factors including: (1) storms such as Nor’Easters and hurricanes, (2) decreased sediment supplies, and (3) sea- level rise contribute to these coastal hazards. Coastal erosion can result in significant economic loss through the destruction of buildings, roads, infrastructure, natural resources, and wildlife habitats. Damage often results from an episodic event with the combination of severe storm waves and dune or bluff erosion. Historically, some of the methods used by municipalities and property owners to stop or slow down coastal erosion or shoreline change have actually exacerbated the problem. Attempting to halt the natural process of erosion with shore parallel or perpendicular structures such as seawalls (groins and jetties) and other hard structures typically worsens the erosion in front of the structure (i.e. walls), prevents or starves any sediment behind the structure (groins) from supplying down-drift properties with sediment, and subjects down-drift beaches to increased erosion. Since most sediment transport associated with erosion and longshore drift has been reduced, some of the State’s greatest assets and attractions – beaches, dunes, barrier beaches, salt marshes, and estuaries – are threatened and will slowly disappear as the sediment sources that feed and sustain them are eliminated. Sandy barrier/bluff coastlines are constantly changing as the result of wind, currents, storms, and sea-level rise. Because of this, developed sandy shorelines are often stabilized with hardened structures (seawalls, bulkheads, revetments, rip-rap, gabions, and groins) to protect coastal properties from erosion. While hardened structures typically prove to be beneficial in reducing property damage, the rate of coastal erosion typically increases near stabilization structures. This increased erosion impacts natural habitats, spawning grounds, recreational activity areas, and public access (Frizzera, 2011). Table 5.2-1 summarizes the number and type of NJDEP shoreline structures off the coastline of New Jersey along the Atlantic Ocean and Inland Bays (current as of 1993). Table 5.2-1 Number and Type of NJDEP Shoreline Structures County Breakwater Groin Jetty Revetment Seawall Atlantic County 0 30 3 0 0 Cape May County 1 94 8 4 3 Cumberland County 0 1 1 0 0 Middlesex County 0 4 0 0 0 Monmouth County 0 172 9 1 11 Ocean County 0 72 3 0 0 Total 1 368 24 5 14 Source: NJDEP 1993 5.2 - 2 5.2 - 2 To counteract the negative impact of hard structures, alternative forms of shoreline stabilization that provide more natural forms of protection can be used. Along the New Jersey coast, beach nourishment and dune restoration are now the main forms of shoreline protection. In addition, existing groins have been notched to reestablish the flow of sediment to previously sand-starved areas of the beach. The sheltered coastlines in New Jersey consist of tidal marshlands and a few narrow, sandy beaches—all of which naturally migrate inland as the sea level rises. Experts have stated that marshes can keep pace with a 0.1 inch per year (inch/year) rate of sea level rise; however, the State’s current rate is approximately 0.11 to 0.16 inch/year, a rate that is predicted to continue increasing (Frizzera, 2011). Currently, bulkheads and revetments are the primary form of shore protection along these tidal areas. As sea level rises and coastal storms increase in intensity, coastal erosion and requests for additional shoreline stabilization measures are likely to increase (Frizzera, 2011). Figure 5.2-1 shows beach nourishment activities in Sea Girt, New Jersey. Figure 5.2-1 B each Nourishment Activities in Sea Girt, New Jersey Source: NJDEP, 2012 Sea Level Rise In the previous plan, 2012 National Oceanic and Atmospheric Administration (NOAA) projections for Sea Level Rise were referenced. The National Oceanic and Atmospheric Administration (NOAA) at the time identified four (4) scenarios for global mean sea level rise in its 2012 report, “Global Sea Level Rise Scenarios for the United States National Climate Assessment”. Based on these four scenarios, labeled “Lowest”, “Intermediate -Low”, “Intermediate-High” and “Highest”, NOAA estimated, factoring in future potential conditions, global sea level rise by the year 2050 at the following four levels, respectively: 0.3 feet; 0.7 feet; 1.3 feet; and 2.0 feet. There is currently no coordinated, interagency effort to identify agreed upon estimates for future sea level rise. The United States National Climate Assessment Development and Advisory Committee, a federal committee writing the next National Climate Assessment, outlines sea level rise scenarios in the National Oceanic and Atmospheric Administration’s Office of Oceanic and Atmospheric Research, Climate Program Office, Technical Report OAR CPO-1 entitled ‘Global Sea Level Rise Scenarios for the United States National Climate Assessment’. For this plan update, more recent and localized projections from Rutgers University are referenced for the State of New Jersey. Local and regional sea level projections for New Jersey are summarized in a 2016 Rutgers University Science and Technical Advisory Panel (STAP) Report, entitled, Assessing New Jersey’s Exposure to Sea-Level Rise and Coastal Storms: Report of the New Jersey Climate Adaptation Alliance Science and Technical Advisory Panel (Kopp et al., 2016). This STAP Report was requested by the New Jersey Climate Adaptation Alliance, which is a network of policymakers, public and private sector practitioners, academics, nongovernmental organizations, and business leaders designed to build climate 5.25.2 -- 33 STATE OF NEW JERSEY 2019 ALL-HAZARD MITIGATION PLAN change preparedness capacity in New Jersey. Projected sea level rise estimates for New Jersey from the STAP Report are presented in Table 5.2-2. Table 5.2-2 Projected Seal Level Rise for New Jersey Central 1-in-20 1-in-200 1-in-1000 Likely Range Estimate Chance Chance Chance 50% probability 67% 5% probability 0.5% probability 0.1% probability Year SLR meets or probability SLR SLR meets or SLR meets or SLR meets or exceeds… is between… exceeds… exceeds… exceeds… 2030 0.8 ft 0.6 – 1.0 ft 1.1 ft 1.3 ft 1.5 ft 2050 1.4 ft 1.0 – 1.8 ft 2.0 ft 2.4 ft 2.8 ft 2100 2.3 ft 1.7 – 3.1 ft 3.8 ft 5.9 ft 8.3 ft Low emissions 2100 3.4 ft 2.4 – 4.5 ft 5.3 ft 7.2 ft 10 ft High emissions Estimates are based on Kopp et al. (2014). Columns correspond to different projection probabilities. For example, the ‘Likely Range’ column corresponds to the range between the 17th and 83rd percentile; consistent with the terms used by the Intergovernmental Panel on Climate Change (Mastrandrea et al., 2010). All values are with respect to a 1991-2009 baseline. Note that these results represent a single way of estimating the probability of different levels of SLR; alternative methods may yield higher or lower estimates of the probability of high-end outcomes. Source: Kopp et al., 2016 The state is consistently applying Sea level Rise projection tools to inform the development of this plan. In addition, as part of the State’s comprehensive effort to assess the potential long term efficacy and fiscal sustainability of specific risk reduction measures and improvements using CDBG funding, the State intends to uses available tools to consider the impact of potential sea level rise and consider whether project designs should be enhanced to address potential sea level rise scenarios, where such enhancements are cost effective and reasonably practical given the inherent uncertainty in sea level rise modeling. 5.2.1.1 REGULATORY PROGRAMS Section 3 Coordination of Local Planning discusses the regulatory programs in place that protect the New Jersey coast. The two main programs are summarized below. New Jersey Shore Protection Program The New Jersey Shore Protection Program was created to provide for the protection of life and property along the coastline, to preserve vital coastal resources, and to maintain safe and navigable waterways throughout New Jersey. The Bureau of Coastal Engineering, which operates under the Office of Engineering and Construction within the New Jersey Department of Environmental Protection’s (NJDEP) Natural and Historic Resources Group, is responsible for administering beach nourishment, shore protection, and coastal dredging throughout the State. The Bureau also maintains the State’s aid to navigation, provides 24-hour operation of the Raritan Bayshore Floodgate, and conducts storm surveys, damage assessments, and emergency repairs for coastal storms that impact New Jersey (NJDEP, 2012).