1
Introduction
On 2 January 1987, during a severe northeaster, a breach formed through
Nauset Spit near Chatham, MA. The initial opening (approximately 20 ft (6 m)
during this storm. The storm surge allowed waves to cut through a low point in
the dune and overwash the barrier spit into the Chatham Harbor/Pleasant Bay
estuary. The storm duration was sufficiently long to allow waves to completely
breach the spit. This initial opening into the back-barrier bay enabled the ebb and
flood tidal flow to further scour out the breach, forming a new inlet. The inter-
action between waves and tides increased the inlet size to 2 miles (3.2 km) wide
within the first 2 years (U.S. Army Engineer Division, New England, 1989).
With the new inlet in place, large changes occurred to the adjacent barrier and
mainland shorelines. Major shoal areas developed both on the ocean and bay side
of the inlet (Liu et al. 1993). The inlet throat widened as both adjacent barrier
shorelines retreated into the bay as recurved spits. The newly formed ebb and
flood shoals grew in area and volume indicating a trapping of littoral sediments
within the inlet system and an influx of ocean sediments entering the bay through
the new inlet. The main ebb channel through the throat of the inlet migrated
southward due to the predominant southern longshore drift. From breach forma-
tion in 1987 until 1992, Chatham Harbor was part of a four inlet system composed
of the established Chatham Bars Inlet opening to the Atlantic Ocean at the south
end of the existing Nauset Spit, Morris Island cut between Morris Island and
North Monomoy Island, and an unnamed inlet between North and South
Monomoy Islands. The new inlet, to the north, bisected Nauset Spit and the
southern portion of the barrier spit became a barrier island completely detached
from the mainland. As the inlet migrated southward, the north end of this south
barrier island retreated into the bay and finally attached to the mainland beach in
the vicinity of the Chatham Lighthouse in early 1992. At that time, Pleasant Bay
estuary became a one-inlet system, with its entire tidal prism opening to the ocean
through the new Chatham Inlet. The main ebb channel continued to migrate south
until early 1995 when a new ebb channel opened through the north swash plat-
form. At the present time there are two ebb channels in the ebb shoal.
As the inlet continued to evolve, the north flood shoal increased in size and
migrated northward. Navigation into the anchorage at the Fish Pier in Aunt
Lydia's Cove became increasingly difficult as the north flood shoal and the Tern
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A table of factors for converting non-SI units of measurement to SI units is presented on page ix.
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Chapter 1 Introduction
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