Living Shorelines in Connecticut

Beaches and Dune

Several options are available for addressing beach and dune erosion; the most appropriate method will depend on site specific conditions. There are many parameters to consider before selecting a Living Shoreline approach.  Some questions to ask are:

1.       Is there an existing coastal engineering structure (seawall, groin, revetment, etc.) at the site?

The presence of an existing engineering structure may affect the coastal processes at the site and must be considered before an appropriate living shoreline approach can be determined. If the structure is functioning as designed, or easily repaired, the most appropriate approach may be to do nothing or repair the structure, while considering alternatives for future needs. See Currently Defended Shorelines for more information on coastal engineering structures.

2.       Is there a sand dune at the seaward edge of the property? If so, is it vegetated? If not, is a dry beach present (sand above normal high tide)? If yes, how wide?

An existing dune indicates the suitability and viability of dune restoration at the project site. The presence of vegetation on the dune not only provides an indication of the stability of the dune system, but is important when creating a dune restoration and planting plan.

If the beach is not currently backed by a dune, there needs to be sufficient dry beach width to create a dune system. In some areas, beach nourishment may be permitting which could extend the width of the beach to allow dune creation.

3.       Is there evidence that your dune or backshore is regularly overtopped and overwashed by waves, and/or that flooding occurs landward of the dune or beach crest? During normal or spring tides? Storm surges?

The frequency of dune or backshore overtopping and flooding is important when determining the necessary elevation of coastal protection to mitigate coastal inundation.

4.       Does the dune and beach naturally gain sand after each winter season?

Beach and dune systems change in response to seasonal variations in waves, wind, tides, and storm surge, transforming from a. wider, flatter “summer” beach to a narrower, steeper “winter” profile. Because the Connecticut shoreline is protected from ocean winds by Long Island, the seasonal variation in winds is less pronounced than on more exposed shorelines. It is important to consider seasonal variations in beach profile when selecting and designing a Living Shoreline.

5.       Is the beach eroding? If so, what is the rate of erosion and what is causing it?

Do nothing or dune vegetation management may be suitable approaches for a stable beach/dune system with little to no erosion. With higher rates of erosion, it is necessary to determine what is causing the erosion. Mitigating erosion from frequent boat wakes may indicate a different approach than one used to reduce storm flooding and wave damage.

6.       Is there infrastructure at risk?

If the existing infrastructure cannot be moved back or up, it may be necessary to select an approach that would provide more protection than a non-structural approach. Evaluation of the site may determine that a living shoreline approach is unsuitable.

7.       What is the wave climate?

The wave climate is a critical parameter in determining the most appropriate approach to shoreline protection. Vegetation-only approaches are usually only suitable for site exposed to low wave heights. The wave climate will determine the type of living shoreline, and the height and composition of the protective structure. Fetch, the distance wind blows of water, is frequently used as an estimate of the wave conditions at a site.

8.       What is the boat traffic?

Some sites, particularly those along navigable rivers streams, may experience larger waves due to boat wake than wind waves. The proximity to a powerboat marina or navigational channel, and the frequency and size of vessels are an important design consideration.

9.       Is the site affected by tidal, riverine or alongshore currents?

Nearshore currents can scour protective structures and transport fill material away from the project site.

10.   What is the shoreline geometry?

The Connecticut shoreline of Long Island Sound is highly variable. The shoreline geometry may be straight, curved or irregular. This high variability is one reason why the most suitable approach to shoreline protection is so site-specific. A headland beach (also known as a pocket beach) is generally crescent or crenulate-shaped, bounded by protective headlands so the shoreline is relatively protected and the sediment supply usually remains between the headlands. A straight shoreline is more exposed to large waves and transport of sediment away from the site.

11.   What is the intertidal slope/nearshore bathymetry?

The intertidal slope and nearshore bathymetry determine the size of the waves at the shoreline. A gradually sloping nearshore region will cause larger waves to break further offshore, reducing the wave energy at the beach. Steep nearshore bathymetry will allow larger waves to break on the beach. Larger winter waves or storm waves typically transport available sand offshore, forming protective sand bars.

12.   What is the tidal range?

The tidal range will impact the height and location of the shoreline protection approach. Most of the existing living shoreline structures have been constructed in areas with low tidal ranges on the order of a couple of feet. Tidal ranges along the Connecticut shoreline vary from about 2.4 ft in Stonington to 7.5 ft in Greenwich. In addition, storm surge heights are typically larger in Connecticut than where living shorelines have been constructed previously.

13.   Is the project site affected by ice?

The Connecticut coast is affected by ice damage, exacerbated by nor-easters and tidal flow. The approach selected must withstand anticipated ice forces at the site.

14.   Does the site have submerged aquatic vegetation or nearshore oyster beds?

Submerged aquatic vegetation or the presence of nearshore recreational oyster beds may affect the type of living shoreline that can be permitted at the site.

15.   What is the composition of the nearshore region?

Some soils may not be able to tolerate the weight of living shoreline approaches such as marsh sills or reef balls. Settling of the structure could render it ineffective. The presence of offshore vegetation or aquatic species may be negatively impacted by the living shoreline. For instance, fill material could bury aquatic plants and animals, or sills and breakwaters could damage nearshore habitats.

16.   How will the shoreline be used?  

The intended use of the shoreline may affect the suitable types of living shoreline. For instance, swimming and boating require different access to the water than fishing or nature watching. The selected type of living shoreline must be compatible with the intended usage of the shoreline.

17.   What is the condition of the adjacent properties?

Depending on the width of the project site, the condition of adjacent properties may affect the suitability of living shoreline approaches. For instance, traditional, hard coastal protection structures may limit the effectiveness of a living shoreline.

18.   Is the project site accessible from land or water?

Access to the project site will affect the cost and constructability of a living shoreline.

19.   What are the potential effects of sea level rise on the project site?

Depending on the anticipated lifetime of the living shoreline, the effects of sea level rise on the erosion mitigation approach may be a selection factor.

A printable checklist of design considerations can be found here.

Some of the options for mitigating coastal erosion on beach and dune systems are not eroding include:

• Do Nothing
• Vegetation Management

For beaches with low waves and limited boat traffic, gradual nearshore and insufficient land to create a dune system:

• Do Nothing
• Plant Native Vegetation
• Beach Nourishment
• Wave Attenuation Devices
• Breakwaters

• Dune Creation or Restoration