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Beach Grading Summary and Discussion
Overall, the beaches in southern Maine, based on volunteer profile data collected, have recovered relatively well from the Patriots' Day Storm of 2007, scoring an overall grade of B/B- (see Table 3). It appears that some of the beach profiles were adversely affected by spring storms in April and May 2008, and the same months in 2009. These later storms may have had a negative impacted on the overall grade of individual profiles. One of the limitations of using "snapshot" points in time (such as the same month through consecutive years, as is the case in this report) is that the analysis may miss, or overly weigh, a certain profile shape that was influenced by an event immediately preceding the recording of the beach profile, when a month later, the profile may show full recovery.
In the two years since the Patriots' Day Storm there were other spring storm events of lesser magnitude that influence this inter-annual analysis. In many locations the profiles also showed variable responses to storms in the spring of 2008 and 2009. Spring 2008 had 10 storms from March through May that had waves of 1 m (3.3 feet) or more. In March 2008 there were six such storms (with beginning dates of March 1, 5, 8, 15, 19, and 26) most of which lasted two days with the exception of March 26-28 with a longer duration storm. These storms had wave heights that peaked from 2.0 to 3.3 m (6.5 to 11 feet). Two storms on April 6 and 27 each lasted three days with wave heights of 2.2 m (7 feet) and 3.0 m (10 feet) respectively. May 2008 had a stormy period from the 10th to the 14th with waves on the order of 1.5 m (5 feet) to 2.0 m (6.5 feet) and a short storm around the 27th with 1.7 m waves (5.6 feet).
The spring of 2009 was marked by 8 moderate storms in March, one large and two moderate storms in April, and two smaller storms in May. As in 2008, the March 2009 storms were spaced evenly through the month at about three or four days apart with waves commonly 1.5 m (5 feet) to 2.0 m (6.5 feet). The largest March storm peaked on March 25th with waves reaching 3.1 m (10 feet). Around April 4, 2009 storm waves peaked at 2.4 m (8 feet) and on April 7 waves reached 3.2 m (10 feet). These back-to-back storms led to erosion without any time in between for the beach to recover. The strongest April storm occurred on April 21 with waves of 3.5 m (11 feet). On May 6, 2009 a storm generated waves of 1.9 m (6 feet). Less than two weeks later a storm created waves of 2.2 m (7 feet). While significantly smaller than the Patriots' Day Storm, these spring storms also reduced or postponed the recovery of several beaches to spring 2006 sand levels.
Some of the beaches have recovered from the Patriots' Day Storm naturally, with little anthropogenic influence or effort. However, Willard Beach in South Portland owes much of its recovery to teamwork and guidance of the Willard Beach Management Plan (Wiper and others, 2008), which stipulated the replanting of dune grass, dune restoration, and beach access path rerouting. All of these actions apparently had a positive influence on the beach, considering Willard Beach saw upwards of 40 feet of dune erosion as a result of the Patriots' Day Storm (Slovinsky, 2007). Similarly, the dune construction project at Ferry Beach in Saco resulted in notable recovery at one of the profiles in the area (FE04). Similar efforts in other communities also led to positive post-storm recovery in the beach and dune system.
The volunteer profiling program has been instrumental in documenting the impacts - and subsequent recovery - of the beaches of Maine after the Patriots' Day Storm of 2007. Locations such as East Grand Beach in Scarborough demonstrated typical barrier island and frontal dune transgression in response to the storm, with the entire profile, including the dune crest, shifting up and in a landward direction, and then recovering as sediment is dispersed along the profile. This response is expected in beach systems that have an adequate supply of sediment. East Grand Beach is at the northern end of Saco Bay, which historically has been the "downdrift" end of the bay, so sand migrates to this area from the southern end of the bay.
Conversely, the responses at Saco's Ferry Beach profile locations were quite different. The frontal dunes exhibited by the profiles prior to the storm were completely wiped out. Although overwash did occur, there was little vertical buildup of dune elevation in response to the event, like that recorded at East Grand Beach. Also, many of the Ferry Beach profiles have not fully recovered, which is likely the result of a negative sand budget at this end of the bay. Similarly, although located in more of a pocket, the profiles at Scarborough Beach have been struggling to recover, demonstrating similar profile responses, with only satisfactory dune regrowth and stability.
Data indicate that Scarborough Beach, which is a generally isolated but long pocket beach, underwent large amounts of erosion, and only demonstrated limited to satisfactory recovery from the storm. This may be due to the fact that Scarborough Beach faces generally due east, and may have taken the brunt of wave attack during the Patriots' Day Storm and subsequent northeast storms from 2008 and 2009.
The volunteer profiling program has also been important in monitoring the fate of beach nourishment. At Ferry and Western Beaches in Scarborough, the profiles clearly show stability and growth at Ferry Beach, while the profile at Western Beach (which was nourished in 2004; Slovinsky, 2006) was eroding. The sediment eroded from the Western Beach berm that was created by the beach nourishment project has been entering the inlet and supplying sediment to Ferry Beach.
Some of the beaches with seawalls recovered from the Patriots' Day Storm rather well. Locations such as Wells Beach and Goochs Beach, which are heavily engineered with seawalls, appeared to have gained sand back after the storm event. Pre-storm elevations, for the most part, were met, and sometimes exceeded at these locations, with the post-storm profile typically being well exceeded, indicating good recovery. This is a welcome result, considering the potentially negative influence of seawalls on the fronting beach.
Even though beaches with seawalls recovered somewhat from the Patriots' Day Storm event, when compared with the pre-storm 2006 shapes some net lowering of the overall profile elevations did occur. Comparison with pre-storm shapes may indicate whether or not a profile is able to recover to a "pre-storm" baseline, instead of a "post-storm" (or erosive) baseline.
For example, although some recovery from the storm did occur, profiles at GO03 (Goochs) and GO04 (Middle Beach) never returned to pre-storm shapes. The same occurred at seawalled locations along Drakes Island Beach (DI03 and DI04), where post-storm recovery was quite minimal, and the pre-storm shapes were not even nearly achieved. These areas may need more time to fully recover.
The same lack of recovery occurred at profiles recorded along naturally vegetated dune stretches of shoreline. This was most notable for the profiles at the Ferry Beach, Saco area, where the only dramatic positive recovery was a result of anthropogenic influences (beach and dune restoration); the remainder of the profiles showed little to no recovery from the storm. This likely reflects the general lack of sediment at the southern end of the bay, while impacts at the northern end of the bay appeared to be more minimal, and recovery much better.
Last updated on November 19, 2009
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