TR-08-13

CMS-Wave: A Nearshore Spectral Wave Processes Model for Coastal Inlets and Navigation Projects

Abstract

The U.S. Army Corps of Engineers (USACE) plans, designs, constructs, and maintains jetties, breakwaters, training structures, and other types of coastal structures in support of Federal navigation projects. By means of these structures, it is common to constrain currents that can scour navigation channels, stabilize the location of channels and entrances, and provide wave protection to vessels transiting through inlets and navigation channels. Numerical wave predictions are frequently sought to guide management decisions for designing or maintaining structures and inlet channels.

The Coastal Inlets Research Program (CIRP) of the U.S. Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL), in collaboration with two universities in Japan, has developed a spectral wave transformation numerical model to address needs of USACE navigation projects. The model is called CMS-Wave and is part of Coastal Modeling System (CMS) developed in the CIRP. The CMS is a suite of coupled models operated in the Surface-water Modeling System (SMS), which is an interactive and comprehensive graphical user interface environment for preparing model input, running models, and viewing and analyzing results. CMS-Wave is designed for accurate and reliable representation of wave processes affecting operation and maintenance of coastal inlet structures in navigation projects, as well as in risk and reliability assessment of shipping in inlets and harbors. Important wave processes at coastal inlets are diffraction, refraction, reflection, wave breaking, dissipation mechanisms, and the wave-current interaction. The effect of locally generated wind can also be significant during wave propagation at inlets.

This report provides information on CMS-Wave theory, numerical implementation, and SMS interface, and a set of examples demonstrating the model’s application. Examples given in this report demonstrate CMS-Wave applicability for storm-damage assessment, modification to jetties including jetty extensions, jetty breaching, addition of spurs to inlet jetties, and planning and design of nearshore reefs and barrier islands to protect beaches and promote navigation reliability.

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.

Chapter 1 - Introduction

• Overview
• Review of wave processes at coastal inlets
• New features added to CMS-Wave

Chapter 2 - Model Description

• Wave-action balance equation with diffraction
• Wave diffraction
• Wave-current interaction
• Wave reflection
• Wave breaking formulas
  • Extended Goda formula
  • Extended Miche formula
  • Battjes and Janssen formula
  • Chawla and Kirby formula
• Wind forcing and whitecapping dissipation
  • Wind input function
  • Whitecapping dissipation function
• Wave generation with arbitrary wind direction
• Bottom friction loss
• Wave runup
• Wave transmission and overtopping at structures
• Grid nesting
• Variable-rectangular-cell grid
• Non-linear wave-wave interaction
• Fast-mode calculation

Chapter 3 - CMS-Wave Interface

• CMS-Wave files
• Components of CMS-Wave interface

Chapter 4 - Model Validation

• Case 1: Wave shoaling and breaking around an idealized inlet
• Case 2: Waves breaking on plane beach
• Case 3: Wave runup on impermeable uniform slope
• Case 4: Wave diffraction at breakwater and breakwater gap
• Case 5: Wave generation in fetch-limited condition
• Case 6: Wave generation in bays
• Case 7: Large waves at Mouth of Columbia River
• Case 8: Wave transformation in fast mode and variable-rectangular-cell grid
• Case 9: Wave transformation over complicated bathymetry with strong nearshore current
  • Extended Miche formula
  • Extended Goda formula
  • Battjes and Janssen formula
  • Chawla and Kirby formula

Chapter 5 - Field Applications

• Matagorda Bay
• Grays Harbor Entrance
• Southeast Oahu coast

Preface

The Coastal Inlets Research Program (CIRP) is developing and supporting a phase-averaged spectral wave model for inlets and nearshore applications. The model, called CMS-Wave is part of the Coastal Modeling System (CMS) for simulating nearshore waves, flow, sediment transport, and morphology change affecting planning, design, maintenance, and reliability of federal navigation projects. This report describes the theory and numerical implementation of the CMS-Wave interface in the Surface-water Modeling System (SMS), and contains examples to demonstrate use of the model in project applications.

The CIRP is administered at the U.S. Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory (CHL) under the Navigation Systems Program for Headquarters, U.S. Army Corps of Engineers (HQUSACE). James E. Walker is HQUSACE Navigation Business Line Manager overseeing CIRP. Jeff Lillycrop, CHL, is the Technical Director for the Navigation Systems Program. Dr. Nicholas C. Kraus, Senior Scientists Group (SSG), CHL, is the CIRP Program Manager.

The mission of CIRP is to conduct applied research to improve USACE capabilities to manage federally maintained inlets, which are present on all coasts of the United States, including the Atlantic Ocean, Gulf of Mexico, Pacific Ocean, Great Lakes, and U.S. territories. CIRP objectives are to advance knowledge and provide quantitative predictive tools to (a) make management of federal coastal inlet navigation projects, principally the design, maintenance, and operation of channels and jetties, more effective and reduce the cost of dredging; and (b) preserve the adjacent beaches and estuary in a systems approach that treats the inlet, beaches, and estuary as sediment-sharing components. To achieve these objectives, CIRP is organized in work units conducting research and development in hydrodynamics; sediment transport and morphology change modeling; navigation channels and adjacent beaches; navigation channels and estuaries; inlet structures and scour; laboratory and field investigations; and technology transfer.

This report was prepared by Drs. Lihwa Lin, Coastal Engineering Branch and Zeki Demirbilek, Harbors, Entrances and Structures Branch, both of ERDC-CHL, Vicksburg, MS; Drs. Hajime Mase of Disaster Research Institute at Kyoto University, Japan, and Jinhai Zheng, visiting Scholar at Kyoto University, and Fumihiko Yamada of the Applied Coastal Research Laboratory at Kumamato University, Japan.

Work at CHL was performed under the general supervision of Mr. Edmond J. Russo, Jr., P.E., Chief of Coastal Engineering Branch, Dr. Donald L. Ward, Acting Chief of Coastal Entrances and Structures Branch, and Dr. Rose M. Kress, Chief of Navigation Division. J. Holley Messing, Coastal Engineering Branch, Navigation Division, CHL, typed the equations and format-edited the report. Mr. Thomas W. Richardson was Director, CHL, and Dr. William D. Martin was Deputy Director, CHL, during the study and preparation of this report.

COL Gary E. Johnston was Commander and Executive Director of ERDC. Dr. James R. Houston was Director of ERDC.