Evaluation of Channel Shoaling and Efficiency of Wideners: DMS Application to St. Marys Entrance, Florida

This study was conducted to understand the causes of entrance channel shoaling at St. Marys Entrance, Florida and to develop alternatives for reducing the frequency and cost of dredging. Diagnostic Modeling System (DMS) methodology was applied to complete the study. The DMS methodology facilitated identification of excessive shoaling areas, gave insight into the causes of shoaling, and aided in development of management strategies for the channel. The analysis documented two areas of shoaling, one in the inner channel, near the seaward end of the jetties and the other in the outer channel, just seaward of the ebb shoal. The inner channel shoaled about 5,700 cu yd/year/200 ft and the outer channel shoaled about 12,000 cu yd/year/200 ft. The inner channel also had a small area of severe shoaling due to sand wave migration into the channel. A localized channel widener is suggested for the inner channel, and advance dredging is recommended for the outer channel.