INLET-INDUCED SHORELINE CHANGES: BOGUE ANDNEW RIVER INLETS, NC

摘要

All developed shorelines in the study area are experiencing problems related to inletinducedrnerosion. The intent of this paper is to provide an overview of two distinctlyrndifferent inlets (Bogue and New River Inlets) within diverse coastal settings where erosionrnmitigation scenarios differ significantly in impact and scale. Bogue Inlet, one of the largerrnwave-influenced transitional inlets separates Bogue Banks from Bear Island. The inlet isrncharacterized by an exceptionally wide throat (~2,590m), a relatively narrow ebb channelrn(~213m), and a large mid-inlet shoal. Since the mid 1970’s the inlet has migrated ~646mrntoward Bogue Banks and as a consequence ~158m of erosion has occurred along therneastern inlet shoreline (Bogue Banks) while the Bear Island inlet shoreline has erodedrn~472m. A highly asymmetric ebb-tidal delta shape has developed and the shape changesrnthat have occurred in the ebb delta have promoted significant shoreline accretion (15.2 –rn125m) along a 1.5km section of Bogue Banks. In marked contrast, the shape changes havernled to shoreline losses (21 – 161m) along a 1.5km segment on Bear Island. Relocation ofrnthe ebb channel to an optimum mid-throat position offers the best means of mitigation.rnNew River Inlet separates North Topsail Beach and Onslow Beach. The inlet hasrnmigrated southward a net distance of 375m. Erosion rates have increased substantially onrnthe updrift barrier. More than 300m of erosion have occurred at a distance of 1.5km fromrnthe inlet. Migration of the inlet coupled with the expansion of the updrift marginal floodrnchannel produced an ebb-tidal delta that was skewed toward North Topsail Beach.rnBetween 1963 and 1995 a 1.5km long segment of Topsail Island prograded as much asrn75m. However, since the mid 1990’s rapid erosion has characterized this reach as thernouter bar channel deflected toward the updrift barrier. Expansion of the southern marginalrnflood channel has resulted in 45m of erosion. In May 2002 the shoreline was nourishedrnwith ~ 200,000m3 of material in an effort to provide temporary protection. The only viablernoption for restoring this shoreline reach to its former configuration involves the relocationrnof the outer bar channel to a position and orientation it occupied in the early 1990s.