State of Maine's Beaches in 2007

Scarborough Beach, Scarborough

Background geology and characteristics

Figure 20	Scarborough Beach is an approximately 2200 m long beach located on the eastern side of Prouts Neck, anchored by bedrock at both ends. An offshore shoal shelters part of the beach from waves, thus creating a seaward-shaped bulge in the beach (Nelson, 1979). This effectively divides the beach into two distinct areas based on sediment characteristics: north of the bulge, the beach is dominantly sandy. South of this point, the beach is composed of a mix of cobbles, sand, and gravel.
	Historically, Scarborough Beach is relatively stable to slowly eroding. Occasionally, old salt marsh peat is exposed in the surf zone. This indicates that the beach was once an open barrier with a back barrier lagoon and salt marsh (Nelson and Fink, 1980). Over time, the dunes have retreated up and over the old salt marsh, along with the beachface.
	Scarborough Beach has 4 measured beach profiles, SC1-SC4. SC1 and SC2 are located on the northeastern side of the main dune walkover, while SC3 and SC4 are located on the southwestern side of the walkover. All transects start behind the crest of the frontal dune (Figure 20). The beginning marks were surveyed by MGS in June 2006.

Annual and seasonal beach profile changes

Beach profiles along Scarborough Beach all start behind the frontal dune crest. Data at SC1 were available for 1999-2000, and 2004-2007. It appears that the beach at SC1 generally went through some accretion from 2004-2006, and erosion during 2007 (Figure 21). This is likely due to the fact that the 2007 data include only data from winter months (ending in April 2007 with the Patriots' Day storm). Annualized profiles from 2004-2006 show very little overall variability, with changes on the order of less than 0.2 m. Seasonally, SC1 does not appear to vary much (Figure 22). Both the mean profiles for summer and winter are about the same, and the profile envelopes only vary slightly from each other. They do, however, indicate that profiles during both seasons can have changes on the order of up to about 1 to 2 m in elevation. Standard deviation values indicate that the majority of nearshore vertical changes are less than 40 cm for both summer and winter. In winter, the variations increase markedly offshore, up to about 75 cm (Figure 23a). This is consistent with winter bar formation.

Annualized mean data at SC2 show that sediment was lost from the profile between 1999-2000 and 2005-2006 (approximately 1 m vertically along the profile, Figure 24). It appears that a portion of the dune was lost during this time as well. The annual profile for 2007 shows additional loss of about 1 m between 2006-2007, likely due to influence from the winter data collected in 2007 and the Patriots' Day storm. Profile SC2 shows slightly more of the typically seen seasonal variability - that is, a more developed berm and more sediment on upper portions of the profile in the summer months versus the winter months (Figure 25). The winter seasonal profile shows greater envelope variability, up to about 3 m, while the summer profile appears to not change as much. Both summer and winter profiles have large standard deviations, on the order of 75 cm, which indicates that the profile is highly variable (Figure 23b).

For SC3, the mean profile from 1999 appears to have started at a different location; therefore it is difficult to compare to the other annualized data from 2000 onwards (Figure 26). In general, there is consistent loss of sediment from the overall profile from 2000-2007, though there appears to be some growth of the sand dune. 2007 again had the least sediment in the profile, likely due to the winter bias of the data. Seasonal data (Figure 27) indicate that the summer profile, as could be expected, contains more sediment out to about 100 m, and that sand is typically lost from this portion of the profile in the winter. The large envelope and standard deviation associated with the summer data may be caused by the inclusion of 1999 data, which was collected during the summer months from a different benchmark. Envelope variability for the winter data is on the order of 1 m, with vertical standard deviation data approaching 50 cm (Figure 23c).

Annualized data for SC4 indicate that the overall profile has lost sediment over time, especially from about 20 m from the pin and seaward (Figure 28). There was stability between 2005-2006 in the upper portion of the profile (to about 35 m offshore), and then sediment gain in the outer portions. From 2006 to 2007 the entire profile underwent erosion. SC4 displays little seasonal variability (Figure 29), in both the mean profile shapes and the profile envelopes. It seems that slightly more extreme maximum and minimum values occur in the winter data (over 1 m), while the summer envelope of values appears to be on the order of 1 m or less. Standard deviation data for both are quite similar along the profile, but highly variable, with the majority of variability on the order of around 50 cm or less (Figure 23d).

Data at Scarborough Beach indicate that the beach undergoes typical seasonal changes and that the beach is generally stable. However, some of the profiles indicate a steady landward transgression of the beach, mostly in response to larger storm events.

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Last updated on January 3, 2008