Waves, Currents, and Suspended Sediment Measurements Around Hybrid Nature-Based Solutions

Hybrid nature-based solutions (NbS) are constructed features that bring together natural and structural elements to attenuate wave energy while providing habitat functions. A major purpose of hybrid NbS is to address shoreline erosion which depends on wave activity and tidal currents. NbS have been the subject of many studies in recent years, particularly their performance in terms of wave attenuation. However, current and sediment dynamics around NbS have not been quantified well. Assessing the hydrodynamics of the flow around NbS enables a better understanding of how they affect nearshore circulation, support vegetation, and ultimately reduce erosion by preserving sediments. In this paper, we report a series of field measurements including wave, current, and suspended sediment concentration (SSC) around a hybrid NbS composed of a low-crested breakwater (or sill), and a fringing planted marsh behind it, as well as around a set of oyster bags installed in the vicinity of the first feature. The study site is located in a rural area in Gloucester County in southeast Virginia, United States. We used a suite of high-frequency pressure sensors, acoustic Doppler current profilers (ADCP), and Turbidity sensors to collect data around these. The measurements show that the marsh+stone sill NbS dissipates both wave energy and currents effectively. However, oyster bags dissipate waves weakly. Furthermore, preliminary analysis reveals a weak correlation between significant wave heights and turbidity.