Tanya M Beck

A depth-averaged 2-D model of flow and sediment transport in coastal waters

A depth-averaged 2-D model has been developed to simulate unsteady flow and nonuniform sediment transport in coastal waters. The current motion is computed by solving the phase-averaged 2-D shallow water flow equations reformulated in terms of total-flux velocity, accounting for the effects of wave radiation stresses and general diffusion or mixing induced by current, waves, and wave breaking. The cross-shore boundary conditions are specified by assuming fully developed longshore current and wave setup that are determined using the reduced 1-D momentum equations. A 2-D wave spectral transformation model is used to calculate the wave height, period, direction, and radiation stresses, and a surface wave roller model is adopted to consider the effects of surface roller on the nearshore currents. The nonequilibrium transport of nonuniform total-load sediment is simulated, considering sediment entrainment by current and waves, the lag of sediment transport relative to the flow, and the hiding and exposure effect of nonuniform bed material. The flow and sediment transport equations are solved using an implicit finite volume method on a variety of meshes including nonuniform rectangular, telescoping (quadtree) rectangular, and hybrid triangular/quadrilateral meshes. The flow and wave models are integrated through a carefully designed steering process. The model has been tested in three field cases, showing generally good performance.

LONG-TERM MORPHOLOGICAL MODELING AT COASTAL INLETS

Abstract : The U.S. Army Corps of Engineers Coastal Modeling System (CMS) is used to simulate the long-term morphodynamics of coastal barrier-inlet systems.The CMS consists of an integrated numerical modeling system for simulating wave, current, water levels, sediment transport and morphology change. In order to quantify the physical effects of long-term, regional climactic changes in the environment, numerical morphodynamic models must be able to reproduce the known generic characteristics that drive barrier inlet processes, including equilibrium inlet dimensions and sediment budget for the tidal shoals. In this study, model results are presented for a 10-year simulation of an idealized inlet and bay system with dimensions similar to that of Humboldt Bay, CA. The model reproduces reasonably well several geomorphic and hydrodynamic features of the inlet at Humboldt Bay. The model results demonstrate the feasibility of applying the CMS for simulating long-term morphology at coastal inlets for practical applications.

Long-Term Morphology Modeling for Barrier Island Tidal Inlets

The U.S. Army Corps of Engineers, Coastal Inlets Research Program, conducted at the U.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, has developed the Coastal Modeling System (CMS) as a coupled wave, hydrodynamic, and sediment transport numerical modeling system. The primary focus of this study is to validate CMS for long-term applications through simulations of tidal inlet evolution and verify the results against established theoretical and empirical formulations that describe the stability and equilibrium conditions of tidal inlets. A wide range of conditions are chosen to test the breadth of model applicability including varying waves, tide and inlet geomorphic characteristics. The model is run for 100 years and the resulting morphological state is gauged in terms of inlet stability theory. Overall, CMS compares well to theoretically and empirically predicted inlet cross-sectional areas with some noted deviations due in part to the artificial nature of the idealized inlet geometry. The sharp spatial transition at either end of the inlet throat leads to artificially large gradients that may increase erosion and associated cross-sectional area. The results suggest that CMS can efficiently and accurately, to the degree of available empirical information, quantify long-term evolution of barrier island tidal inlet systems. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/CHL TR-18-12 iii

Merrimack Estuary and Newburyport Harbor sediment management studies

This report documents a numerical modeling study investigating sediment transport and morphology change adjacent to Merrimack Inlet, Newburyport, and nearshore in the vicinity of Salisbury Beach and Plum Island, Massachusetts. Concerns at the site include beach erosion, shoreline retreat on Plum Island downdrift of and within the inlet, and reduced navigability of the inlet. The numerical modeling evaluation consists of two phases. The Phase I study was conducted with the damaged and partially rehabilitated South Jetty between 2012 and 2014, and the Phase II study was conducted with the fully rehabilitated South Jetty between 2015 and 2016. Historical hydrodynamic and sediment data in the study area were assembled, and a field data collection program was carried out. The datasets were used to develop a coastal wave, hydrodynamic, and sediment transport model. Different alternatives were developed to evaluate sediment management strategy and structure modification, and the calculated bed sediment volume changes of each alternative were compared with the results under base (existing) condition. Alternative simulations demonstrated the Coastal Modeling System capability in evaluating beach erosion, structure performance, sediment transport, and morphology change in the inlet and estuarine system. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/CHL TR-18-7 iii

Field measurements, sediment tracer study, and numerical modeling at Coos Bay Inlet, Oregon

This report documents a field data collection program, including the sediment tracer study, and numerical modeling investigation for dredged material placed in the nearshore area of an ocean dredged material disposal site (ODMDS) adjacent to Coos Bay Inlet, OR. The collected data around the inlet system were assembled, analyzed, and used to calibrate and validate the Coastal Modeling System (CMS) and the Particle Tracking Model (PTM). Sediment transport pathways and fate of placed material were evaluated. The model and sediment tracer study results indicate that the tracer placed within the nearshore ODMDS primarily moves alongshore towards the inlet at the initial stage of the release. Material arriving at the inlet channel and ebb shoal is jettisoned offshore by strong ebb currents. The results also show that the sediment tracer spreads northward alongshore due to strong dominant southerly wind across the inner continental shelf. At and outside the inlet, finer particles are transported the farthest offshore and away from the navigation channel and nearshore ODMDS area. A new sediment mapping technique applied in model simulations demonstrates migration and burial for sediments placed in the nearshore ODMDS. Both CMS and PTM results compare well with those of the sediment tracer study. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR. ERDC/CHL TR-18-6 iii

Sediment Tracer Tracking and Numerical Modeling at Coos Bay Inlet, Oregon

ABSTRACT Li, H.; Beck, T.M.; Moritz, H.R.; Groth, K.; Puckette, T.; Marsh, J., and Sánchez, A., 2019. Sediment tracer tracking and numerical modeling at Coos Bay inlet, Oregon. Journal of Coastal Research, 35(1), 4–25. Coconut Creek (Florida), ISSN 0749-0208. An investigation was conducted on transport of dredged material placed in the nearshore area of an ocean dredged material disposal site (ODMDS) adjacent to the Coos Bay inlet, Oregon. A sediment tracer release/sampling and field data collection program was carried out and a numerical hydrodynamic, wave, and sediment transport model, the Coastal Modeling System, was developed to perform the analysis of sediment transport around the inlet system and the ODMDS. The data were used to calibrate and validate model calculations, and the model was set up to calculate sediment fluxes and to simulate the process of sediment tracer release and movement, and determine the pathways of sediment tracer under combined wave, current, and wind conditions within and around the immediate vicinity of the Coos Bay ODMDS. The calculations and the measurements indicate that sediment tracer movement is primarily controlled by tidal current inside Coos Bay and at the inlet entrance, and responding to wave and storm conditions in the open coastal area. A divergence in net sediment transport directions in the adjacent nearshore beach was apparent in the results of the tracer release and numerical simulations. This methodology may be used to determine sediment bypassing pathways and optimal placement of sediment within a nearshore environment adjacent to tidal inlets.