First Year Performance of Two Beach Nourishment Projects with Different Sediment Grain Size, West-central Florida Ping Wang1, Katherine E. Brutsche1, and Tiffany M. Roberts2

First Year Performance of Two Beach Nourishment Projects with Different Sediment Grain Size, West-central Florida
Ping Wang¹, Katherine E. Brutsche¹, and Tiffany M. Roberts²

1: Department of Geology, University of South Florida, Tampa, FL 33620, [e-mail]

2: Department of Geology & Geophysics, Louisiana State University, Baton Rouge, LA 70803

Sand Key, a barrier island in Pinellas County, Florida was nourished in 2005 and 2012. The two nourishments are nearly identical in terms of project area, constructed berm height, and berm width. The two nourishment projects used different borrow areas which resulted in beach fills with very different sediment grain size. The 2005 nourishment used sand from the ebb shoal at Pass-A-Grille inlet, which led to largely uniform fine sand across the entire project. The 2012 nourishment used sand from various offshore sand bodies, which resulted in substantial alongshore variations in grain size ranging from fine sand to sand with high contents of large gravel. The two nourishment projects were monitored using same beach profiles surveyed at similar time intervals. This study quantifies and compares the first-year performance of the 2005 and 2012 nourishment projects based on the surveyed beach profiles.

The entire Sand Key nourishment project is 14 km long. A total of approximately one million cubic meters of sand were places. Based on the background erosion rate, the constructed berm width varied along the project. For the convenience of discussion, the entire Sand Key nourishment project is divided into four segments, including: 1) North Sand Key: a short beach with a net northward longshore transport (a reversal from the regional southward transport), 2) Indian Rocks Beach: a relatively straight and long beach with net southward longshore transport, 3) Indian Shores: a broad headland beach, and 4) Redington Beach: a straight and long beach with net southward longshore transport. North Sand Key is an erosional hot spot with a much wider constructed berm width than the rest of the project, approximately 80 m versus 30 m. The 2012 nourishment used much coarser sediment with limestone gravel and large conk shells along this stretch than the 2005 project.

An intensive monitoring study was conducted to quantify the performance of the beach fills. The study includes monthly to bi-monthly surveys of 75 beach profiles spaced at 300 m or less, spanning the entire Sand Key barrier island. Traditional level-transit surveys were conducted using a 4-m survey rod to reach water depth of about 3 m, or roughly the closure depth in this area. The CMS-WAVE model was used to examine wave patterns along the curved coast under representative wave conditions, e.g., northerly waves accompanying the passages of cold fronts. Wave conditions measured at two offshore NDBC buoys were compiled to compare incident wave energy at the project area during the first year post nourishment. Bi-month beach-profile volume and shoreline changes were calculated.

The full presentation will discuss the performance of each segment for the 2005 and 2012 beach nourishments. The influence of different sediment grain size on the performance of the beach nourishment will be discussed in detail.
Biography of the Presenter
Ping Wang is the director of the Coastal Research Laboratory and an Associate Professor at the Department of Geology at the University of South Florida. Wang obtained his Ph.D. in Coastal Geology from the University of South Florida in 1995. Wang’s research interest includes: coastal sedimentary processes, nearshore sediment transport, nearshore wave and current dynamics, coastal morphodynamics, coastal engineering and management, numerical modeling of coastal environments. Impact of the BP oil spill to beach environments is the new “research adventure” by Wang and his research team. Wang and Dr. Nicole Elko co-led the field trip for the 2009 ASBPA national conference.