CAREER: The influence of turbulence to mass transport in complex aquatic habitats

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Economic and ecosystem resilience are closely connected in coastal regions, where development as well as hydrologic hazards (storm surge, flooding, erosion) are intensifying. Ecosystem-based protections near waterbodies, such as living shorelines, oyster reef and mangrove forest, are increasingly sought to enhance resilience to these climatic hazards; however, restoration projects and ecosystem-based defenses often fail because current understanding of erosion and sediment transport is based on simplified models of non-vegetated channels. This research will develop new scientific knowledge to illuminate effects of three-dimensional canopies (oyster reefs, seagrass beds, mangroves) on turbulent flow, movement of sediments, and sequestration of Blue Carbon (peat deposits). Using both laboratory flume and field experiments, the PI will test novel sediment transport theory within these complex natural habitats. Societal benefits of better understanding of erosional processes at vegetated river banks and shorelines are vast and transferable to aquatic systems around the world, allowing managers of vulnerable areas to plan impactful restoration projects and management strategies to mitigate effects of flooding, bank erosion, or sea level rise. The project will engage diverse students in an experiential ‘boots in-the-mud’ study of aquatic systems by integrating research and field-based learning with classroom instruction at a variety of educational levels, including middle/high school, undergraduate, and graduate students, and professionals. A Living Ecohydraulics Laboratory on an island in the field study area is where the next generation of student scientists will be trained at the intersection of ecology and engineering. This research will develop and test cutting-edge sediment transport theory, elucidating the roles of shear stress and turbulence on mass transport within diverse, complex aquatic habitats. In the field, the PI will test the hydrodynamic and sediment transport effects of 1) submerged, rigid canopies of oyster, 2) submerged, flexible canopies of seagrasses, and 3) emergent canopies of mangrove. Mass transport within these functionally diverse canopy types will be related to turbulence through field-coupled laboratory experimentation. Better understanding of shear stress-turbulence relationships for sediment transport across varied canopy types and flow regimes will fundamentally change the way that sediment transport is modeled in complex canopies and will significantly advance predictive ability regarding erosional and depositional processes in natural waterbodies. Newly-developed sediment transport understanding will be linked to its applications in ecosystem restoration and design of nature-based infrastructure to promote greater resilience to climatic hazards. Educational activities include establishment of an island Living Ecohydraulics Laboratory to engage over 1400 learners and immerse 250 students into aquatic research sites over the life of the project. The integrated research-educational field experiences are targeted at influential academic stages, including middle-high school science research programs and summer camps, to attract and retain students who may have otherwise not chosen STEM careers. Display of middle and high school research projects in high-traffic community spaces will effectively engage community members in the research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.