Tidal inlets, which are dynamic and often ephemeral features of coastline geography, form a direct and essential connection between inland bays, lagoons, and the open ocean, and are often used as navigation channels. More than 95% of international freight and 2.3 billion tons of international and domestic commerce pass through coastal inlets, and thus the United States Army Corps of Engineers (USACE) spends in excess of $1 billion on inlet maintenance (Hughes and Kraus, 2006). To retain safe and navigable passages, it is necessary to fully characterize inlet hydrodynamics, which determines sediment transport patterns and morphodynamics. We propose to develop and test a remote system for continuous synoptic measurements of currents and volumetric discharge (the total volume of water flowing through a cross section at a given instant in time) over a range of conditions in a tidal inlet. To develop this system, we will obtain observations needed to improve the understanding of the vertical flow structure in inlets (to relate surface flows to depth-averaged flows) and to understand the relationship between the length scale of surface turbulent eddies and flow depth.
A remote system capable of synoptic measurements of currents and volumetric discharge will provide significant cost savings over traditional in situ measurements. It will greatly enhance our ability to monitor the ongoing behavior of tidal inlets and their response to large storm events and anthropogenic inputs (such as dredging) and is an ideal platform for the long term assessment of the evolution of coastlines. The system that is developed here will enable timely and accurate assessment of coastal management strategies, thereby ensuring the ongoing use of tidal inlets as avenues of commercial and recreational navigation. Moreover, the completion of this project will lead to the development of an innovative methodology that will revolutionize our current understanding of the fundamental processes, which influence and shape the morphodynamics of not just tidal inlets but of coastlines as well.
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