the shoal lost area and volume and became somewhat attached to the mainland
beach, shoaling the west flood channel. By 1989, the west channel opened again
as the shoal continued to gain sand and expand laterally on both the east and west
sides. While maintaining a teardrop shape and near constant area, the shoal began
to migrate up-estuary between 1989 and 1991.
In 1991, a flood ramp started to form on the western side of the shoal closest
to the inlet and expanded northward almost bisecting the shoal by 1995 (Fig-
ure 44b). This ramp formation corresponded with the closing off of the south
Chatham Harbor by the welding of the South Beach to the mainland. All the tidal
flow was now directed north into Chatham Harbor and Pleasant Bay. In 1994, the
west ebb spit had migrated close to the mainland shore, with growth of the ebb
shield on the north side. This process had restricted the flow through the west
channel and shoaling resulted in the channel. The first spillover lobe formed on
the ebb shield as the west channel tried to re-establish. This growth and shoaling
make navigation difficult into Aunt Lydia's Cove. It necessitated the dredging of
the entrance channel in 1995, which can be seen partially completed through the
west ebb spit. The flood ramp grew to the north in 1996, again almost cutting the
flood shoal in two, in an attempt to naturally re-establish the west channel. This
channel had became narrowed and was forced by the ebb shield to occupy the
remnants of the east-west entrance channel as it flowed around the large ebb
shield and down the west side of the west ebb spit. In 1988, the flood shoal again
expanded in area and volume, after several years (1992-1997) of near constant
area and volume. The north flood shoal has expanded in width and length as it
almost fills the entire north Chatham Harbor. Its shape has changed as it took on
more characteristic flood shoal features over time.
A new spillover lobe began forming by ebb currents trying to cut the shoal in
half, to re-establish the main west flood channel in 1997. This lobe was located on
the western side of the ebb shield, close to the preinlet west channel center line.
This spillover lobe has grown in 1998 and 1999 to become a major feature on the
north side of the flood shoal and has almost divided the shoal in half by 1999. The
flood shoal continues to increase in area and volume with growth northeastward
up-estuary. The east-west entrance channel to the Fish Pier anchorage has been
pushed toward Tern Island and finally almost shoaled in. The west side of the
shoal has migrated west and is almost attached to the mainland beach. To main-
tain access, a new channel has been cut in a northwest-southeast orientation on the
lower west ebb spit just off Claflin Landing by the county through the thinnest
part of this west ebb spit.
66
Chapter 4 Ebb and Flood Shoal Evolution
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