The influence of tidal inlet migration and closure on barrier planform changes : Federal Beach, NC
- UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
- Emerson G. Hasbrouck (Creator)
- Institution
- The University of North Carolina Wilmington (UNCW )
- Web Site: http://library.uncw.edu/
Abstract: Federal Beach, a narrow 10 km-long barrier spit that connects the Fort Fisher
headland and the Cape Fear foreland, has been breached numerous times during the past
centuries. Prior to 1880 the storm breaches served as one of several conduits for the
exchange/discharge of the Cape Fear River. One long-lasting breach that opened in 1761
near the headland evolved into the second largest inlet system in the area until it was
artificially closed by the U.S. Army Corps. of Engineers in 1880. Closure was
accomplished by the construction of a 4.6 km-long dam that dramatically reduced the
tidal prism and the extent of the ebb tidal delta. Long-lasting impacts associated with
inlet closure include the chronic erosion of the headland area and frequent breaching of
the barrier and the subsequent rapid migration of small inlets. Concurrent with inlet
migration is the realignment of the barrier spit shoreline.
A GIS-based analysis of aerial photographs from 1938 to 2005 was conducted to
quantify shoreline rate-of-change values for the barrier spit, and migration rates of the
associated inlet systems. The Federal Beach barrier spit shoreline accreted an average of
6 m, at a rate of 0.1 m/yr during this period. This study identifies two shoreline change
zones (SCZ). SCZ I is characterized as a retrograding reach, with long-term erosion
averaging 78 m from 1945 to 2005. Over the same period, SCZ II is characterized as a
prograding reach, with long-term accretion averaging 69 m.
Two inlet systems, New Inlet A (NIA) and New Inlet B (NIB) were active along
the Federal Beach barrier from 1938 to 1999. The NIA system opened in the 1890’s and
by 1959 had migrated approximately 6 km to the south where the system closed due to
shoaling of the inlet throat. New Inlet B opened in 1944 and closed in 1999. During this period the NIB system migrated south a total of 6 km, at a mean rate of 106 m/yr. Both
the size and stability of the New Inlet B system was determined to be strongly influenced
by the morphology of the backbarrier environment with respect to inlet position.
As both of the New Inlet systems migrate along Federal Beach they actively
reshape the barrier spit planform, resulting in the progradation of the updrift barrier
shoreline. Anthropogenic and natural changes to the backbarrier environment have
impacted the behavior of the inlet systems, consequently resulting in long-term changes
of the Federal Beach barrier spit planform.
The influence of tidal inlet migration and closure on barrier planform changes : Federal Beach, NC
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Created on 1/1/2009
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Additional Information
- Publication
- Thesis
- A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
- Language: English
- Date: 2009
- Keywords
- Littoral drift--North Carolina--Federal Beach, Coast changes--North Carolina--Federal Beach
- Subjects
- Coast changes -- North Carolina -- Federal Beach
- Littoral drift -- North Carolina -- Federal Beach