RAPID: Hurricane Harvey Rapid Response: In-Situ Barrier Island Storm Impact and Recovery Measurements of Hydrodynamics, Morphodynamics, and Sedimentation Acr. Hog and F. Island TX

Texas A&M Engineering Experiment Station, College Station TX

Investigators

Abstract

Rapid response field measurements of extreme storm impacts to coastal systems are difficult to obtain due to short advance notice times for deployment, potential for instrument failure or loss, and uncertainty in actual storm impact for specific locations. This project advances capabilities to measure detailed hydrodynamic processes (currents and waves) across the surface of barrier island systems impacted by extreme events. The data will provide unprecedented information to enhance and ground-truth predictive modeling capabilities of storm impacts. Detailed analysis of immediate and medium term (weeks to months) recovery of the two selected field sites (Hog and Folletts Islands) will shed further light on post-storm recovery dynamics of barrier island systems that are critical to understand in the context of relative sea level rise and the potential for more frequent and/or intense tropical storms. In turn, this knowledge can help bolster the resiliency of coastal communities. The research team was able to deploy a set of five "Rapid Response Units" (RRUs) along the central and upper Texas Gulf coastline three days prior to Hurricane Harvey's landfall as a Category 4 storm on August 25, 2017. The RRU sites provide detailed measurements at two locations roughly half way between the landfall point and Galveston, and enable detailed comparative studies of the storm's impacts on these two systems. The RRUs contain pressure transducers to record water level fluctuations and wave heights, tilt current meters to measure current and orbital wave velocities, acoustic Doppler velocimeters, and GoPro time-lapse imaging systems. These data will be interpreted in the context of pre- and post-storm digital elevation models (DEMs) generated using an unmanned aerial system (UAS) and standard photogrammetric processing algorithms. Post-storm rapid response activities also include subaerial and wading-depth real time kinematic (RTK) beach profile transects and surface sediment sampling and coring of washover deposits. An initial program of weekly UAS flights, followed later by monthly surveys, would document recovery of the barrier system following the hurricane.