CAREER: Multi-scale Interactions of Waves, Currents and Morphology with Application to Rip Currents

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0845957 YuThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Coastal erosion has increasingly become a concern due to rising global sea levels, changing climate and accelerating human activities. The hydrodynamics in the surf zone has significant influences on nearshore sediment transport, hence shoreline erosion, and on the transport and mixing that affect the water quality in coastal oceans and floodplains. Understanding the complex dynamics of the nearshore system is of fundamental relevance to the development of reliable predictive tools for planning, management and mitigation to build a sustainable and resilient coastal environment. This study aims to improve this understanding by investigating the multi-scale interactions among three key nearshore processes: waves, currents and sediment transport. Rip currents, an important nearshore process, are also a dangerous beach hazard, accounting for 80% of surf zone rescues in the US. Theoretical understanding of their generation mechanisms has not been satisfactory, in particular on beaches lacking alongshore variability. Recent studies have mostly focused on morphodynamic instabilities, stressing the feedback between currents and sediment transport but not fully considering the dynamical interaction between waves and currents. This research will investigate all multi-scale interactions. The research will use extensive linear instability analysis, numerical modeling of the nonlinear multi-scale dynamics, and model validation through comparisons with observations. The methodology developed here will be applicable in modeling other environmental systems including estuaries and floodplains. Research and education will be fostered by developing a graduate research program and curriculum in coastal dynamics and environmental fluid mechanics. This will rejuvenate undergraduate education in fluid mechanics at NC State to stress its role in natural environments. Key concepts of coastal engineering research will be brought into the K-12 science curriculum by direct interaction with teachers through a collaborative initiative. Further broad impacts are expected through the outreach programs of the PI's collaborators, including the National Weather Service, Army Corps of Engineers Field Research Facility, Sea Grant and UNC-Coastal Studies Institute.This project is being co-funded by the Engineering, Geosciences, and Cyber Infrastructure Directorates.