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Variation of Beach Morphology along the Saco Bay Littoral Cell:
An Analysis of Recent Trends and Management Alternatives


by

Peter A. Slovinsky
Stephen M. Dickson

Maine Geological Survey
Open-File 03-78

Online Edition, 2005


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Abstract

Sandy pocket-beaches comprise only about 2 percent of the Maine coastline; however, they provide numerous economic, environmental, and recreational benefits. These beaches are typically confined into 'littoral cells' by tidal inlets and rocky headlands. Saco Bay, which includes approximately 8 miles of arcuate sandy shoreline, is bound by Fletcher Neck and the Saco River in the south and the Scarborough River and Prouts Neck in the north. This shoreline comprises the largest sand beach and salt marsh system in Maine. The primary source of sediment to the beaches in the bay is the Saco River (Kelley and others, 1995). The bay exhibits a dominant northerly-directed longshore transport direction (Barber, 1995; Kelley and others, 1989).

In 1869, the United States Army Corps of Engineers (Corps) initiated construction of shore-perpendicular jetties in an attempt to stabilize the inlet to prevent channel shoaling, and provide safe navigation for shipping. The structures have impeded the natural flow of sediment into the bay system, diverted sediment farther offshore and into deeper water, disrupted the existing ebb-tidal delta, and made the onshore movement of sediment much more difficult. It appears that the federal jetties have caused accelerated erosion rates on the order of 2-3 feet per year at Camp Ellis, a small beachfront community situated adjacent to the northern jetty (Duffy and Dickson, 1995). Substantial environmental, economic, and social impacts have resulted from erosion that has claimed over 30 homes in the last 100 years at Camp Ellis. The problem continues today, amplified each winter season by northeast storms that batter the southern Saco Bay shoreline with swells and storm surge.

Existing morphologic trends, topographic features, and shoreline types along the Saco Bay shoreline were identified using Light Detection and Ranging (LIDAR) data, aerial photographs, and field inspections. Shorelines from aerial photographs were digitized and recorded in the field using a global positioning system (GPS), and shoreline changes determined. By combining shoreline changes with beach profile data, volumetric estimates of changes in the subaerial-to-intertidal beach were made. Future positions of shorelines and areas possibly susceptible to flooding were projected using this data set. Coastal hazards were identified and preliminary beach management guidance provided.

The Corps, in association with local stakeholders, federal, and state agency personnel, are currently developing mitigation plans for Camp Ellis Beach under Section 111 of the Rivers and Harbors Act. Finally, alternative scenarios proposed by the Corps to alleviate erosion at Camp Ellis Beach are presented and discussed.

Table of Contents

Introduction

Historical Background

  • Jetty Construction
  • Dredging and Beach Nourishment
  • Previous Studies
  • Regional Planning

Methods

  • Coastline Orientation
  • Sea Level Rise
  • Estimated Net Erosion and Accretion
  • Shoreline Type, Dry Beach Width, and Total Landward Width to Structures
  • LIDAR Analysis

Results

  • Coastline Orientation
  • Sea Level Rise (1962-1995)
  • Estimated Net Erosion and Accretion (1962-1995)
  • Shoreline Type, Dry Beach Width, and Total Landward Width)
  • Alongshore Variation of Beach Profile Shapes
  • Mean Profile Shapes
  • Variation of Maximum Profile Elevations (MPE) in Reference to Base Flood Elevations (BFE)
  • Variation of Overall Beach Profile Slopes
  • Estimated Net Volume Changes (1962-1995)

Discussion

  • Region 1 (Hills Beach)
  • Region 2 (Camp Ellis Beach, Ferry Beach, Bay View, and Kinney Shores)
  • Region 3 (Ocean Park, Old Orchard Beach, Surfside, Grand Beach, Pine Point)
  • Region 4 (Western Beach)
  • General Discussion
  • Identification of Regions of Potential Concern
  • Data and Method Limitations
  • Correlations

Recommendations

  • Regional Sediment Management
  • Elevating above Base Flood Elevations
  • Widening Dry Beach Widths
  • Increasing Total Landward Widths
  • Plan for 100-yr Erosion
  • Plan for 100-yr Accretion
  • Consider Shoreline Structure Maintenance or Removal
  • Proximity to Tidal Inlets
  • Section 111 Plan Alternatives: Coastal Engineering and Mitigation at Camp Ellis

Conclusions

Recommendations for Additional Study

Continued Research

References

Appendix A - LIDAR Images

Funding for this report was provided by the Maine Coastal Program, Maine State Planning Office under the Coastal Zone Management Act of 1972, as amended, pursuant to Award No. NA17OZ2336 administered by the Office of Ocean and Coastal Resource Management, National Oceanic and Atmospheric Administration.

Additional support for this study was through a Coastal Management Fellowship Award No. NA87OC0490 provided by the Coastal Services Center, National Oceanic and Atmospheric Administration to the Maine Geological Survey for a project entitled Creating a Sustainable Beach Community at Camp Ellis, Maine from August 2001 through July 2003.

Last updated on January 9, 2006