297
FitzGerald and Pendleton
Figure 6.
1993 and 1999 vertical aerial photographs of New Inlet depicting changes to the flood-tidal delta, swash platform and recurved
spit, and main ebb channel and ebb-tidal delta system. Note that by 1999 a short-cut channel had formed across the spit platform
and that sandbars were migrating onshore to the downdrift shoreline.
the inner inlet channel was controlled by the location and
the bay tidal prism. At most migrating inlets a breach
configuration of the flood-tidal delta and position of the spit
through the spit platform is tantamount to closure of the old
platform and recurved spit system.
channel and bypassing of the sand comprising the severed
As viewed in the 1993 aerial photograph, the ebb spits of
platform. This process has not occurred at New Inlet due to
the flood delta and the westerly extent of the spit platform
a growth spurt of the updrift spit, which amounted to 0.4 km
funneled ebb flow in the main channel toward the southern
between 1999 and 2001. Progradation of Nauset Spit has
end of the spit platform (Fig. 6). However, by 1999 the
deflected the main channel to the more southerly course
flood delta had migrated 327 m northward and the landward
causing inefficient flow between ocean and bay.
extent of the spit platform was displaced southward. This
Consequently, the old main channel has been rejuvenated,
movement of shoals changed the direction of ebb discharge
while moderate tidal flow persists through the new channel
coming out Pleasant Bay. The end result was a deflection of
(Fig. 5). Moreover, the inlet continues to bypass sand in
ebb flow off the mainland headland to a route across the spit
relatively small quantities in the form of individual swash
platform (Fig. 6). Erosion in the channel next to the
bar 100 to 300 m in length welding to the beach every 1 to
headland reached depths over 12 m. Some of this scoured
3 years.
sand was transported southward forming a broad sand shoal
that partially filled the outer main ebb channel. As shoaling
in the old main channel continued, the new channel through
the spit platform captured an increasingly larger portion of
Journal of Coastal Research, Special Issue 36, 2002
Previous Page
