Navigating Dynamics: Sediment Transport Modeling at Sturgeon Point Marina

Abstract: GZA modeled sediment transport around a marina in Lake Erie using the SWAN (Simulating WAves Nearshore) model and the CMS (Coastal Modeling System)-Flow/CMS-Wave coupled model and used them to inform alternative marina structure designs to limit sedimentation and future dredge operations in the marina. Sturgeon Point Marina in Evans, NY, built in 1988, is the only harbor of refuge between Buffalo Harbor and Sunset Bay Harbor. The marina is a significant regional asset, yet since its construction it has had sedimentation issues, blocking navigation and marina access to a very important Lake Erie harbor. On an annual basis, sand has been dredged from both the sandy beach to the west of the marina and from the mouth of the marina and has been placed onshore to the East of the marina. GZA conducted a metocean data analysis of the site and acquired and modified elevation data for input into a seamless bathymetric digital elevation model. ASCE-7 wind data was used to gather wind characteristics at the site for use in numerical modeling and the Sturgeon Point NOAA Tide Guage was used for water level analyses. Both 10- and 20-year annual exceedance probability conditions were developed for wind, waves, and water levels. From USACE hindcasting Wave Information Study (WIS) points, GZA concluded that the dominant wave direction for daily and storm conditions are from the Southwest, with some North and Northeast wave/wind events being seen to cause nearshore morphology changes. GZA developed a SWAN-2D wave model to model waves from the offshore WIS points to the nearshore. GZA then developed a CMS-Wave and CMS-Flow model, using nearshore results from SWAN-2D to simulate waves, flow, and sediment transport in a smaller area around Sturgeon Point Marina. GZA studied 6 scenarios that were combinations of the wave/wind directions of concern, the 20-year and 10-year wave/wind conditions, and the 20-year, 10-year, and average water level conditions. Results from the numerical modeling indicate that during high-water, Southwest wave conditions, sediment was transport west along the outer jetty, wraps around the jetty toward shore, and then settles in the mouth of the marina. This same sedimentation location was observed during the Northeast wave condition, with sediment pushing from the East into the mouth of the marina. With a better understanding of the sediment transport in and around the current marina structures, GZA completed sediment transport model simulations with 5 different alternative structures/changes in the marina. An intensification of the sediment morphology was utilized to best understand and visualize the nearshore processes. A factor of 5 times was applied (replicating 5 consecutive storm events), and using this method under dominant storm conditions, the addition of a spur jetty to the eastern end of the outer jetty was seen to reduce sedimentation at the marina entrance the most, by about 60%.
GZA has presented these alternatives and all sediment transport analyses in the Master Plan and Revitalization Strategy Report.

Please describe the young professional’s contributions to the project, including but not limited to, building a model, writing a technical report, performing calculations, construction administration and observation tasks, and any aspects of design. (500 words max): Liam Hanley was the staff engineer who, under the direction of Mike Gardner, created and ran the SWAN and CMS models for simulation of current and future conditions, which involved much sensitivity analysis. Liam also calculated volumetric changes and generated a report on these findings