Processes and Patterns of Sedimentation at Blind Pass, Florida

A field-oriented sedimentation study was conducted at Blind Pass Florida, shortly after the last channel dredging in the summer of 2000. Blind Pass is a wave-dominated tidal inlet that has been migrating southward for over 3,000 meters before it was stabilized by a series of hard-engineering structures since 1937. Thereafter , the inlet has been maintained by frequent dredging. The dredged material was typically used to nourish the adjacent beaches, especially the downdrift Upham Beach. T ime-series measurements of tidal currents and bathymetry were conducted in the inlet channel. The ebb-dominated main channel, roughly 6 m deep, extends along the southern side, where peak ebb current approached 150 cm/s. Along the northern side of the inlet, the ebb curre nts are much weaker , as compared to both the flood current and ebb current in the main channel. Shortly after the 2000 dredging, rapid sedimentation was measured along the northern side of the inlet. This accumulation is likely resulted from the predominant southward longshore sand transport, bypassi ng the north jetty . The northern part of the inlet is dominated by flood-directed current and the weak ebb current is not adequate to flush the bypassed sediment out of the inlet. Along the southern side with the deep channel, active sediment flushing is evident as indicated by the coarse, shelly lag deposit on the bottom. Roughly 28 months after the channel dredging, the northern side near the entrance has become shallow enough to induce wave breaking over the shoal. Distinctive seasonal patterns of sedimentation are measured thereafter in the inlet channel, influenced by the seasonal wave climate