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Particle tracer analysis for submerged berm placement of dredged material near South Padre Island, Texas

January 1, 2021

The fate of unconfined dredged sediment placed as a submerged “feeder” berm in the nearshore region of South Padre Island (SPI), Texas, was investigated through a particle tracer study over the duration of 15 months. Unconfined sediment feeder systems can be a desirable alternative to traditional direct beach placement of nourishment material because the feeder systems are less intrusive to the beach environment and often less expensive. Placing sediment as close to the active beach profile, as practicable, and relying on natural nearshore processes to slowly distribute the sediment to the beach can keep a finite resource within the littoral zone. One challenge with this indirect approach is predicting the short- and long-term effects on the coastal system and shoreline in light of the complex nearshore dynamics involved. This study aims at elucidating sediment transport pathways at SPI after tracer release over the feeder berm via assessment of tracer particle counts obtained from nine sediment sampling campaigns (950 surface-sediment grab samples) between August 2018 and November 2019, covering a grid of 60 seabed and 50 dry beach locations. Tracer counts were performed in the laboratory making use of the fluorescent and ferromagnetic properties of the engineered particles to separate them from other sediment material. Results indicate that although the highest tracer counts remained near the initial release site of the feeder berm during the duration of the study, appreciable amounts of tracer moved throughout the study region. Even though fluctuations of tracer migration were observed, the most prominent appearance of tracer particles outside the initial placement site occurred south and immediately west of it, indicating net alongshore and onshore transport in those directions. Relatively, few tracer particles were found on the dry beach, indicating appreciable deposition of feeder material there may take years rather than months.

Publication Year 2021
Title Particle tracer analysis for submerged berm placement of dredged material near South Padre Island, Texas
Authors Jens Figlus, Youn-Kyung Song, Coraggio K. Maglio, Patrick L. Friend, Jack Poleykett, Frank Engel, Douglas James Schnoebelen, Kristina Boburka
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Dredging
Index ID 70227790
Record Source USGS Publications Warehouse
USGS Organization Oklahoma-Texas Water Science Center