Coastal Sediment Availability and Flux (CSAF)

Science Center Objects

Sediments are the foundation of coastal systems, including barrier islands. Their behavior is driven by not only sediment availability, but also sediment exchanges between barrier island environments. We collect geophysical, remote sensing, and sediment data to estimate these parameters, which are integrated with models to improve prediction of coastal response to extreme storms and sea-level rise. 

With a wealth of knowledge about how shorelines, beaches, and dunes respond to storms and the variability of inner shelf geology, the USGS Coastal and Marine Hazards and Resources Program is poised to extend its morphologic and geologic expertise across the shoreface and back-barrier data gaps. Shoreface geology is particularly important to assess since it may record evidence of processes that we otherwise don’t have the opportunities or capabilities to observe. With these goals in mind, we measure geology and morphology in coastal environments to reconstruct past environmental histories and estimate the magnitude and rate of sediment exchanges (e.g., fluxes) over a range of time scales. Integration of these observations with models allows us to predict past and future behavior of barrier-island systems in a changing climate and provides information to help our partners mitigate coastal hazards and identify coastal restoration priorities. 

Project Objectives: 

  • Incorporate shoreface morphology and geology into coastal-change assessments 
  • Conduct repeat geophysical surveys to estimate sediment fluxes with better accuracy and temporal resolution 
  • Understand how coastal systems respond to storms, variations in sediment supply and rate of sea-level rise over short (1-10s year) and long (100-1000 year) time scales 
  • Make predictions of future (long-term) coastal vulnerability and resilience rooted in robust morphologic and geologic observations 


Explore science related to the Coastal Sediment Availability and Flux project:

An island with sections of short grasses has been covered by a large sand fan that was washed landward by waves.


Storm-Related Barrier Island Morphological Evolution - Storms quickly and dramatically alter barrier island environments by changing adjacent seafloor morphology, eroding beaches, scarping or leveling dunes, and sometimes creating new inlets. Measuring the magnitude of barrier island sediment movement during and after storms allows us to track rates of beach recovery, dune growth, and inlet-related alterations to barrier island sediment supply.

Sediment berm along the northern Chandeleur Islands, Louisiana






Barrier Island Sensitivity to Changes in Sediment Supply - Observations and models show that maintaining barrier islands requires a balance between sea-level rise and sediment supply. However, most estimates of sediment supply are not based on modern conditions, which could result in less accurate predictions of sediment fluxes. We explore how natural and human alterations impact modern sediment fluxes, or changes, on barrier islands – research that has important implications for coastal resilience and restoration.

A boat operated by USGS staff tows an instrument that collects geophysical data in in the shallow shoreface near the beach.





Shoreface Morphology and Geology - Exchanges of sediment between the shoreface and barrier islands allow barrier islands to adjust to changes in water level, such as those associated with storms or sea-level rise. Characterizing shoreface morphology and geology allows us to explore how past and present processes have impacted modern barrier island sediment transport and what that means for future barrier island evolution.

Sandy barrier island with dunes near a sandy beach on one side, low vegetation in the middle, and a bay of water on the other.





Modeling Barrier Island Evolution, Shoreface Morphology, and Overwash - Barrier island field observations provide information about past and current environmental conditions and changes over time; however, they can’t tell us about the future. Models can predict possible future behaviors but are only as good as their input data. By integrating both observations and models, we can extend observations and arrive at more realistic predictions of barrier island behavior and vulnerability to storms and sea-level rise.

Scientists operate scientific sediment coring equipment with a tall metal barrel and tripod on a sandy beach near the water.






Coastal Sediment Availability and Flux (CSAF) Capabilities - We use innovative technology and integrate a variety of techniques to characterize barrier island environments, reconstruct their past history, and predict their future vulnerability.