USING DISTRIBUTED FIBER-OPTIC SENSING TO RECORD SANDBAR MIGRATION UNDER CALM AND ENERGETIC CONDITIONS

Sandy coastlines are continually evolving in response to waves and currents, and predicting the evolution of these dynamic regions depends on collecting accurate measurements of sediment-transport processes. It is especially critical to measure the near-bed and shallow- subsurface processes that drive bedload sediment transport. Bedload-transport evolves over a wide range of spatial and temporal scales, which are challenging to capture with sparse instrumentation. Additionally, processes at the seabed are challenging to measure using existing remote sensing techniques, which primarily capture sea surface signal (Holman and Haller, 2013). Distributed fiber-optic sensing is a rapidly evolving field technique with the potential to provide high-resolution spatial and temporal measurements of pressure and temperature at the seabed. These techniques employ laser scattering to record signals at distributed intervals along a fiber-optic cable, such as a seafloor telecommunications cable. Here, we present observations from the combined use of Distributed Acoustic Sensing (DAS) and Distributed Temperature Sensing (DTS) to record near-bed and shallow subsurface dynamics in a sandy, nearshore environment. The focus of this project is to identify the relationships between strain, temperature, and cable burial, which can be used to track bedform migration.