Variation of Beach Morphology along the Saco Bay Littoral Cell

Introduction

The sandy pocket-beaches that comprise only 2 percent of the 3,500 mile Maine coastline 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 shoreline (a littoral cell), is bound by Fletcher Neck and the Saco River in the south and the Scarborough River and Prouts Neck in the north. The bay comprises the largest sand beach and salt marsh system in Maine (Figure 1). The primary source of sediment to the beaches in the bay is the Saco River, which provides an estimated 10,000 to 16,000 m³ of sand per year (Kelley and others, 1995). The bay exhibits a dominant northerly directed alongshore transport direction (Barber, 1995; Kelley and others, 1989). Historically, riverine sediment entered the bay through the Saco River, was stored in an ebb-tidal delta, and wave-action periodically caused shoals to migrate landward and weld onto downdrift beaches.

Figure 1

Figure 2

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, thereby providing safe navigation for shipping. The jetties have precluded the natural flow of sediment into the bay system by diverting sediment farther offshore and into deeper water, making the onshore movement of sediment a much more difficult process. Since construction, the federal jetties have caused accelerated erosion rates on the order of 2-3 ft per year at Camp Ellis, a small beachfront community situated adjacent to the northern jetty (Duffy and Dickson, 1995). Erosion has claimed over 30 homes in the last 100 years at Camp Ellis, and the problem continues today, amplified each winter season by northeast storms that batter the southern Saco Bay shoreline. A 1995 aerial photograph of the Saco River jetties, river channel and adjacent beaches is shown in Figure 2.

The objectives of this report are to

discuss existing morphologic trends and features along the Saco Bay shoreline;
present recommendations for the management of Saco Bay's sandy beaches; and
discuss the status of federal involvement in mitigating shoreline erosion along Saco Bay.

Contents Introduction Historical Background Methods Results Discussion Recommendations Conclusions Additional Study and Research References Appendix A

Last updated on January 9, 2006.