Laudholm and Drakes Island Beaches:
Before and After Beach Nourishment

Background

In the fall of 2000, sand from Wells Harbor (Figure 1; Figure 2) was dredged and pumped onto adjacent beaches. Placement of the dredged sediment on the beach was a low-cost disposal option for the US Army Corps of Engineers during maintenance of a federal channel and anchorage. In less than three months, about 180,000 cubic yards of sediment was pumped through pipelines onto Wells and Drakes Island Beaches from a suction dredge with a rotating cutter head (Figure 3). At the end of a pipe, sand and water slurry was released on the beaches (Figure 4; Figure 5) at various points. As much as 6,000 to 8,000 cubic yards of sand were pumped onto the beach in a day. Dewatered sand was shaped with bulldozers into a higher beach profile with more sand at the high-tide line and in front of seawalls. This nourishment occurred on the higher elevations of the beach profile in the vicinity of the berm, or area of summer sand accumulation.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Purpose

Figure 6

In order to follow the movement of sand on Drakes Island Beach and state-owned Laudholm Beach, the Maine Geological Survey measured beach profiles before the nourishment and three months later. The profile lines used were the same as those used by teams of volunteers from the region who measure the beach monthly (more on volunteer profiling). Here we summarize the changes to the beach profiles on Drakes Island Beach as a result of nourishment and on Laudholm Beach as a result of natural changes without nourishment (Figure 6).

Results

Six beach profiles were measured on 9/20/00, a few days before Wells Harbor dredging began and three months later on 12/19/00, soon after the dredging and beach nourishment were completed. Sand was placed primarily on the beach in the vicinity of Drakes Is. #3 and #4 profiles. No sand was placed directly on the Laudhom profile lines.

Laudholm Beach Profiles #1 (Figure 7) and #3 (Figure 8) showed very little change. A late-summer beach face eroded 20 to 40 cm and the profiles became more convex. There was no immediate gain of sand on the Laudholm profiles as a result of nourishment on Drakes Island.

Figure 7

Figure 8

All of the Drakes Island beach profiles (Figures 9, 10, 11, 12) showed a gain of sand over the three-month period. With the exception of a berm that eroded off Drakes Is. #2, the upper profiles had a smooth slope up to the frontal dune or a seawall. This slope almost certainly formed by wave action two days earlier during the second major fall storm. The artificial berm, built with sand from beach nourishment, had been partially reshaped by waves.

Figure 9

Figure 10

Figure 11

Figure 12

Drakes Is. #2 showed about 80 cm of vertical sand accumulation near the low-tide line. This buildup may be the result of impoundment adjacent to a gravel bar between profile lines #1 and #2. Drakes Is. #1 gained 40 to 75 cm on the beach face, and had the most volume gain of any of the six profiles measured. This accumulation occurred next to the north jetty of the Webhannet River.

Conclusions

The profiles at Laudholm Beach experienced a small loss of sand from the upper portions of the profile in the vicinity of the high-tide line (Figures 7 and 8). This change was most likely due to wave action in recent fall storms. Laudholm did not see any significant buildup of sand due to longshore drift (shore-parallel sand transport) from the beach nourishment area on Drakes Island.

On Drakes Island, beach profiles were altered by the initial placement of sand near the seawalls and frontal dune. In general, the profiles showed some of that sand remained in place after the first two fall storms. The artifical berm (not shown on graphs) however, had been reshaped into a smoother slope. A considerable buildup occurred on the lower portions of Drakes Island profiles #1 and #2 (Figures 13 and 14). This new accumulation is from the redistribution of the nourishment alongshore to the south by the process of longshore drift and down the profile from wave action and the influence of gravity. This pattern of sand transport and accumulation has occurred since the 1960's, soon after the jetties were built (Kelley and Anderson, 2000).

Figure 13

Figure 14

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Related Links:

• Maine Geological Survey Marine Geology Index Page
• State of Maine Beach Profiling Project
• University of Maine Marine Geology Working Group
• U.S. Army Corps of Engineers, New England District
• Rachel Carson National Wildlife Refuge
• Town of Wells, Maine
• Kelley, Joseph T., and Anderson, Walter A., 2000, The Maine Shore and the Army Corps: A Tale of Two Harbors, Wells and Saco, Maine: Maine Policy Review, v. 9, no. 2, p. 20-34.

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Text by Stephen M. Dickson.

Originally published on the web as the October 2001 Site of the Month.

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Last updated on April 23, 2012

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