DEEP: Coastal Hazards Primer - Erosion

Coastal Hazards Primer - Erosion
 
 
Coastal Hazards Primer
 Introduction   Precipitation
 Flooding    Tropical Storms and Hurricanes 
 Erosion   Winter Storms 
  Wind  
 
Wind, waves, tides, and sea level rise, in conjunction with the geology of the Connecticut coastline, have been causing erosion for millennia. Erosion can occur gradually over many years or come and go in cyclic patterns. Storms can create massive amounts of erosion sometimes flattening dunes and gouging beaches in minutes or hours.

Littoral transport, the movement of materials in the nearshore area by waves and currents, can help offset the effects of erosion by accreting sand onto the shore. New sediment is delivered from rivers draining into Long Island Sound or released from the naturally-occurring erosion of coastal bluffs and escarpments.

These materials and their movement make up the sediment budget of the coast.

In the early 1980s the Connecticut Coastal Area Management program developed Planning Report #29: Shoreline Erosion Analysis and Recommended Planning Process that addressed the nature and effects of erosion on the Connecticut coastline. Despite its vintage, the geologic and environmental factors discussed continue to provide a relevant description of coastal processes in Connecticut:

  • Greenwich to Norwalk: Erosion and other significant changes to the shoreline are rare more pronounced are artificial filling of tidal areas. Erosion effects are most pronounced on small beach areas and areas behind them.
  • Norwalk to Milford: This area is significantly impacted by erosion due to high density development and highly erodible barrier beaches.
  • Milford to New Haven: Erosion in beach areas along the north-south trending shoreline has traditionally been a concern and has been aggravated by extensive stabilization of sediment sources in headland areas.
  • New Haven to Guilford: Most of the shoreline is stable. However, beach shorefront in East Haven and the marshes of Chaffinch Island experience the largest erosion effects in this region.
  • Guilford to Old Lyme: Erosion of beaches and low bluffs is common. Structural erosion control efforts such as groins and seawall have altered natural shoreline processes and have aggravated the problem by trapping natural sediment needed for beach replenishment. Several large scale changes in barrier beach configuration, notably Menunketesuck Island and Griswold Point, are evident.
  • Old Lyme to Groton: Generally, no large scale marine erosion effects are evidenced beyond the creation of steep bluffs at the southern ends of headlands (resulting in reduced source materials available to beaches) and along several beach and barrier beach locations.
  • Groton to Stonington: Only one portion of shoreline is considered significantly affected by erosion, the northerly tip of Sandy Point. Most shoreline is protected due to rocky composition.

Attempts to stabilize the naturally dynamic shoreline and control flooding have often complicated erosion problems. Structural protection measures such as seawalls, revetments, bulkheads, groins and jetties may help stop bluffs and stretches of beachfront from eroding, but in nearly all cases they can actually worsen existing erosion or cause new erosion in adjacent sections of the shore. This typically happens in three primary ways. First, hard structures can deflect wave and wind energy onto immediately adjacent sections of shoreline, exerting additional or new erosion forces. Second, they tend to lock up and/or impede the natural flow of sediment along the coast. Lastly, as sea level rises, hard structures can impede the natural functions of tidal wetlands and marshes, reducing their viability as protective buffers to erosion.

Since many flood and erosion control projects are constructed water-ward of the high tide line, the state of Connecticut, through the Office of Long Island Sound Programs (OLISP), has significant power to decide where and how these projects are constructed. The Connecticut General Statutes Section 22a-92(b)(2)(F) and Section 22a-92(b)(2)(J) state:

"Structural solutions are permissible when necessary and unavoidable for the protection of infrastructural facilities, water-dependent uses, or existing inhabited structures, and where there is no feasible, less environmentally damaging alternative and where all reasonable mitigation measures and techniques have been provided to minimize adverse environmental impacts."

In practice, the permitting and enforcement activities of OLISP are consistent with the statutory statement concerning the construction and repair of erosion control structures.

In Summary

What can you do when it comes to the threat of erosion in Connecticut?

  • Be aware that erosion is one of many natural coastal processes inherent with living on the shore.
  • Consult the guidance materials Living on the Shore and the Connecticut Coastal Management Manual to better understand the rights and responsibilities of coastal living.
  • Realize that any activities (construction, operation of machinery, removal/transfer of material, etc.) waterward of the high tide line and in tidal wetlands are subject to regulation by the State.  Before undertaking any activities, be sure to contact the Office of Long Island Sound Programs at 860-424-3034 to find out if your project requires approval.
 
Content Last Updated January 3, 2012