Coastal Sediment Availability and Flux (CSAF) Capabilities

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By St. Petersburg Coastal and Marine Science Center September 15, 2020

As part of the Coastal Sediment Availability and Flux project, we use innovative technology and integrate a variety of techniques to characterize barrier island environments, reconstruct their past history, and predict their future vulnerability.

Geophysics

We acquire geophysical data to investigate changes in the shape and geology of inner shelf, shoreface, beach, and barrier environments. In shallow marine environments, we acquire high-resolution multibeam and single-beam bathymetry – data that show the shape and depth of the seafloor. By repeating surveys in the same location annually or semi-annually, we track erosional or depositional processes that might impact the response of the barrier to storms, sea-level rise, or human intervention. We pair bathymetry with sub-bottom geophysics (e.g., Chirp), to explore sediment layers beneath the seafloor. On land, we examine what’s beneath beaches and barriers using ground-penetrating radar (GPR) to learn about their evolution through time.

Bathymetry of the shoreface of Cedar Island, VA.

Deploying survey equipment at Madeira Beach, FL

Remote Sensing

Remote sensing allows us to assess changes in barrier island extent, inlet dynamics, overwash processes, and land cover at varying spatial scales. Different spectra, or frequency ranges, in satellite imagery help us classify land cover features. This is especially useful for rapidly changing coastal features, like new inlets, where we can use multiple forms of remotely sensed imagery to study their evolution.

Colored lines overlaid on aerial image of an island and island breach shows how the island footprint has changed since 1985. — Fire Island shorelines from 1985 to 2018 were extracted from imagery and are plotted together with 2018 imagery to reveal how a breach in the island has evolved through time. From 1985-2011, the island was continuous at this location. The passage of Hurricane Sandy in 2012 formed a breach in the middle of the island and this breach can be observed in 2018 imagery and shorelines from 2013-2018.

Animation displays an island spit lengthening between the years of 1970 and 2017. — Aerial photos across a 47 year time span show landscape change at the Holgate peninsula on the south end of Long Beach Island, a barrier island in Atlantic County, New Jersey. The peninsula has undergone extension and inland migration since 1970.All of the images are published through the New Jersey Geographic Information Network (NJGIN), at: https://njgin.nj.gov/njgin/edata/imagery/index.html#!/.

Reduced-Complexity Models

We use reduced-complexity models to infer past changes in coastal systems and reconstruct past geomorphology, which can help predict future change. This animation displays modeled beach profile elevation as it has evolved at Parramore Island, Virginia. These data are based on geomorphic field investigations and measure distance (in kilometers) of cross-shore accretion. Q_S is the flux of sand to the beach and Q_D is the flux of sand from the beach to the active dune. Yellow represents sand, blue represents water, while green represents marsh.

Animation of a plot displaying beach elevation over time — Animation displays modeled beach profile elevation as it has evolved at Parramore Island, Virginia. These data are based on geomorphic investigation and measure distance (in kilometers) of cross-shore accretion. QS is the flux of sand to the beach, and QD is the flux of sand from the beach to the active dune. Yellow represents sand, blue represents water, while green represents marsh.

Sediment Sampling

Sediment sampling is used to verify remote sensing observations and can tell us how old sediments are, where they came from, and what processes brought them there. Sediment cores can extend records of erosion and deposition further into the past than geophysical or remote sensing methods.