Seasonal Change in Nearshore and Channel Morphology at Packery Channel, A New Inlet Serving Corpus Christi, Texas.

摘要

Packery Channel is an artificial inlet that occupies a historic ephemeral pathway between Corpus Christi Bay and the Gulf of Mexico. In 2005, the inlet was opened by Hurricane Emily during its construction and has remained open and navigable for more than 4 years. The shallow-draft channel has not required maintenance dredging despite episodic shoaling during storms, including Hurricane Ike. Stability of the inlet and adjacent beach is attributed to location in the southeast corner of Corpus Christi Bay, receiving augmented ebb flow by wind setup accompanying winter fronts. The ebb current, with speed sometimes exceeding 1.0 m/s, scours sediment deposited during the summer months, thereby maintaining channel depth adequate for water exchange and navigation. After the channel opened, a deposition basin initially served as the main sediment repository for sediment scoured from the bay side. Entrance channel shoaling began to increase in 2008, initiated by 15,000 m3 of beach sand that entered the channel during Hurricane Ike. Subsequent shoaling is attributed to unrestricted wind-blown transport enhanced by drought. Since completion of the 430-m long dual jetties in 2006, an ebb-tidal delta has not formed. Ebb delta development is suppressed by a strong longshore current and longshore bar formation that alternates in direction seasonally, and by strong bursts of ebb flow during winter. The inlet is located in a region of nearly balanced longshore sediment transport, indicated by near-symmetric shoreline response at each jetty. The shoreline within a 1-km zone of the inlet advanced at a rate of 7.5 m/yr, whereas along the 18-km monitoring area it receded at a rate of 1.6 m/yr, reflecting in part the influence of Hurricane Ike. Channel performance tracks closely with that reported in the original design, with stability to date exceeding those 1997 predictions.