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East Grand Beach, Scarborough
Background geology and characteristics
Annual and seasonal beach profile changes
Beach profiles along East Grand Beach all start from behind the frontal dune crest. East Grand beach profiles form a continuous dataset from 1999-2007, one of the only locations to do so. At EG1, inspection of the mean profile shapes indicates a well developed dune that has migrated landward slightly and gained elevation consistently over the data collection period (for example, in 1999 the dune crest was located at 40 m from the pin and 2.8 m in elevation; by 2007, the crest was located at 24 m from the pin at an elevation of 3.5 m (Figure 48). This indicates that the dune is migrating landward through the process of overwash, and that enough sediment is available for the dune to gain elevation. The winter and summer mean profiles are extremely similar in terms of overall shape and variability based on envelope and standard deviation data (Figure 49). The berm appears to vary between 25-35 cm vertically, at a position between 20-40 m from the mark (Figure 50a).
Similar to EG1, mean annualized profiles at EG2 show dune growth and landward migration from 1999 (at 35 m offshore and 2.8 m elevation) to a maximum during 2004 (22 m from pin and 3.7 m), with a slight loss in dune elevation from 2004-2007 (Figure 51). Consistent with many other locations, the 2007 overall profile contains less sediment, except for the 2003 profile. There is little difference in the summer and winter mean profile shapes, though the winter profile exhibits a much larger minimum and maximum envelope (Figure 52). Standard deviation variability is larger for the winter profile, up to 50 cm vertically, over a large horizontal area, between 30-110 m from the mark (Figure 50b).
Like the other profiles at East Grand Beach, EG3 underwent similar changes to the dune crest - landward movement and a gain in elevation, with the 2007 profile exhibiting the highest dune elevation (at 3.2 m compared with 2.6 in 1999). Generally, there has been little change to the profile past 50 m from the pin (Figure 53). Seasonally, there is little difference between the summer and winter mean profiles, though the summer profile exhibits a slightly greater volume of sediment along the berm (Figure 54). The maximum variability based on profile envelopes and standard deviations (Figure 50c) is about the same for summer and winter, about 25 cm of vertical variation on average.
Annualized profiles at EG4 (Figure 55) show changes similar to the other 3 profiles; that is, the landward migration and growth of the frontal dune crest. The dune crest, between 1999-2007, migrated about 5 m inland and gained approximately 0.5 m in elevation. The 2003 mean profile was again the "leanest," similar to the other EG profiles. Seasonal data (Figure 56) indicate that the EG4 summer profile exhibits slightly more sediment along portions between 30-120 m from the mark. There is little seasonal variation of the dune shape, and the profile variability envelopes are quite similar, though farther offshore, the variability based on standard deviations increases to near 50 cm vertically (Figure 50d).
The profiles at East Grand Beach appear to be relatively stable, though steady landward migration of the dune crest is apparent in the data. However, the dune crest is gaining in elevation as it migrates landward, indicating enough of a sediment supply to facilitate such processes. This indicates a healthy, yet somewhat transgressive, beach system.
Last updated on January 3, 2008
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