Figure 20. Temporal change in inlet throat width and position of ebb channels with repsect to original
beach location
adjacent barriers rapidly expanded in the first five months to a width of 2,200 ft
(670 m), with a single ebb channel of 350 ft (107 m) that had migrated 850 ft
(259 m) south of the original breach. The inlet steadily widened as both the north
and south spits recurved back and away from the inlet into Chatham Harbor. The
throat reached its widest point in April 1994, measuring approximately 9,700 ft
(2,957 m).
The southern ebb channel which was the only ebb channel at the time,
migrated southward to a maximum of 3,400 ft (1,036 m) south of the original
breach in June 1993. The channel was also at one of its widest points at that time
at 1,250 ft (381 m). This averages out to a southerly migration rate of 567 ft/year
(173 m/year) over the six-year period. The South Beach spit welded to the main-
land beach one year earlier in 1992. The attachment and growth of the sand bridge
restricted further southerly migration of the south channel after June 1993. After
that time, the South Beach grew back to the north, maintaining a position around
3,000 ft (914 m) south of the original breach from March 1996 through 1999. The
Nauset Beach spit also reversed direction growing back to the south after June
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Chapter 3 Inlet Throat, Shoreline, and Channel Evolution
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