Skip Maine state header navigation
Skip First Level Navigation | Skip All Navigation
|Home | Contact Us | Publications|
Ferry Beach, Saco
Background geology and characteristics
Annual and seasonal beach profile changes
The beach profiles at Ferry Beach all start landward of the frontal dune crest. However, Ferry Beach faces acute erosion problems; thus, the beach profile starting point locations have changed numerous times since data collection began, making a set elevation and contiguous analysis much more difficult. Thus, at this point, none of the surveyed elevations have been applied to the data. Data available from the website were also sporadic, with numerous years missing.
Profile FE1 was broken down into FE11 and FE12. FE11 contains data from 2000, 2001, 2003, and 2005, while FE12 has data from 2001-2003; there may be additional beginning points as well. It is extremely difficult to ascertain overall changes at FE11, since it appears that the starting point in 2000-2001 (a front stake) was different than those for 2003 and 2005 (a back stake). There appears to have been slight erosion of the profile between 2000-2001, and more substantial sediment loss and subsequent landward dune migration and slight elevation loss between 2003-2005 (Figure 64). Due to the number of changes in the benchmarks of the starting points, seasonal changes were not analyzed at FE11.
Annualized data for FE12 (Figure 65) showed loss of sediment along the profile from 2001-2002, and then loss of dune between 2002-2003, with the addition of sediment along the offshore portion of the profile (between 8 m and 40 m from the mark). No seasonal or standard deviation data were developed for FE12 due to the inability to relate the number of benchmarks used accurately with the data.
Similar to FE1, profiles at FE2 were collected at several different starting points, a front stake (FS) and a back stake (BS), during different years of data collection. The beach at FE2FS (Figure 66) saw general accretion from 2000-2002, then substantial accretion from 2002-2003 (or possibly the starting point changed). From 2003-2005, the entire profile lost elevation. Seasonal profiles (Figure 67) indicate little difference between the summer and winter profiles or their envelopes. Standard deviation data (Figure 68a) indicate that the winter and summer beach at FE2FS is quite variable during both seasons, varying between 50-75 cm vertically along a large portion of the profile (between 10-50 m from the mark).
The profiles at FE2BS, which were collected from 2005-2007, indicate that the beach underwent little change from 2005-2006 overall; however, in 2007, the dune was eroded by several meters, though there was slight accretion along the berm portion of the profile, between 35 and 55 m from the mark (Figure 69). Seasonal data indicate that there is generally a higher, more developed and stable frontal dune crest in the summer, while the crest is lower and more variable in the winter (Figure 70). During the summer, a slightly more prominent berm appears. Standard deviation data indicate that there is relatively little variability in the summer profile elevations, with only slightly more variability in the winter - at the dune crest, and farther offshore, up to 40 cm of vertical variability (Figure 68b).
At FE3FS, the profile underwent accretion from 2000-2001, stability from 2001-2002, large amounts of accretion from 2002-2003 (unless the starting point changed), and slight erosion from 2003-2005 (Figure 71). The erosion was concentrated at the dune and lower portions of the profile, from 15 m from the starting mark and greater. Seasonally, the winter profile shows a slightly better developed dune, and more sediment storage in the offshore (Figure 72). There does not appear to be much of a berm in either season. Seasonal variability, based on the standard deviation data (Figure 68c), indicates that the beach undergoes relatively major changes in both the winter and the summer, in the dune area (on the order of 50 cm), and into the offshore, up to about 75 cm of vertical variability, especially in the winter. This may be indicated by the erosive nature of the beach during the winter season.
Annualized profiles at FE3BS were collected from 2005-2007. The beach underwent slight accretion at the dune between 2005-2006, and then loss of dune elevation on the order of 0.5 m from 2006-2007 (Figure 73). The portions of the profiles farther offshore seem to have changed little. The winter and summer mean profiles are about the same, though slightly more volume of sediment appears in the berm area of the profile in the summer mean profile (Figure 74). Standard deviation data (Figure 68d) indicate that the summer beach is relatively stable, with variations less than 20 cm along the profile. Winter variability is markedly increased at the dune (changes above 40 cm), and in the offshore, where variations are also on the order of 40 cm. This may indicate that erosion of the dune during winter leads to offshore storage of sediment during the same time period.
Profile FE4 had several different benchmarks over the years, the first from 2000-2003 (labeled as FE4FS), and the second from 2005-2007 (labeled as FE4BS). Annualized mean data for FE4FS (Figure 75) show that the beach underwent accretion from 2000-2001; this accretion continued in 2002. In 2003, the dune and berm underwent erosion from the dune to about the 20 m mark, and accretion occurred seaward of this. Seasonally, FE4FS (Figure 76) displayed more sediment in the dune and the berm in the summer than the winter. According to standard deviation data (Figure 68e), the summer profile exhibits greater variability, up to almost 75 cm at the location of the berm.
Data for the beach at FE4BS (data from 2005-2007) showed that the dune and beach underwent dramatic erosion - complete loss of the frontal dune crest and its elevation, from 2005 to 2006 (Figure 77). This erosion was approximately 4-5 m horizontally and almost 0.5 m vertically. This was likely due to the May 2005 northeast storm. Analysis of seasonal data (Figure 78) and standard deviation data (Figure 68f) for FE4BS shows that the summer profile varies very little, while the winter profile varies greatly (up to 100 cm) in dune elevation and position and along the profile.
The profiles at Ferry Beach exhibit a marked difference seasonally; summer typically tends to see a slightly more developed dune crest and berm, while winter shows an erosive profile, with substantial loss in the frontal dune and berm, with little recovery to pre-winter conditions (though it appears a "new" summer shape follows the next season. This area is heavily eroded during winter storm events, with dune removal on the order of 3 to 6 meters (10-20 feet) during substantial events (i.e., 2005 northeasters and Patriots' Day storm). The fact that profile starting locations have been moved so many times is indicative of the erosive nature of this stretch of beach.
Last updated on January 3, 2008
|Copyright © 2008 All rights reserved.|