LINKAGE BETWEEN EBB CHANNEL DEFLECTION IN UNMODIFIED SYSTEMS AND OCEANFRONT SHORELINE CHANGE: BEAR AND BROWN'S INLETS, NC

Bear and Brown's Inlets are small systems located in the NE sector of Onlsow Bay along the shoreline reach characterized by high relief, sand-rich barriers. Bear Inlet (BEI) separates Bear Island to the NE from Browns Island to the SW while Brown's Inlet (BRI) borders Browns Island on its southern margin and separates the barrier from Onslow Beach to the southwest. Due to their unmodified nature they are exemplary sites to study the linkage between inlet changes and the response of the adjacent oceanfront shorelines.

Both inlets are relatively stable systems having been confined to narrow migration pathways since 1872. Since 1938 the BEI throat segment of the ebb channel has migrated southwestward 2,148 ft at an average rate of 29 ft/yr while the BRI ebb channel has migrated to the SW a distance of 1,265 ft at an average rate of 18 ft/yr. The net migration direction is opposite the inferred direction of sediment transport.

While the position of the throat segment of the ebb channel of both inlets has changed comparatively little (Avg. 82-145 ft) during a short time interval the outer bar segment of the channel shifted across a comparatively wider zone that averaged 1,050 ft. Since 1934 a minimum of six cycles of channel deflection and reorientation have occurred. Consequently the ebb-tidal deltas have undergone significant shape changes which in turn have altered the ebb delta’s breakwater effect along the opposing oceanfront shorelines. The decadal long accretion and erosion patterns are responses to the above mentioned changes. Generally speaking for a given period of time the oceanfront shorelines along the adjacent barriers are characterized by opposing shoreline change patterns.