Wave evolution in river mouths and tidal inlets
Loading...
Authors
Pearman, Douglas W.
Subjects
Wave-current interaction; river mouth; tidal inlet; drifter observation; Lagrangian sensing; refraction; ray theory; extreme waves; rogue waves.
Advisors
Herbers, Thomas H. C.
Date of Issue
2014-06
Date
June 2014
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
Detailed observations of wave evolution and wave-current interaction in tidal inlets and river mouths are essentially non-existent owing to the difficulty of installing and maintaining fixed instruments in this harsh environment. This work develops and explores the use of small, free-drifting buoys to collect wave and current measurements in coastal inlets. The instruments, referred to as Wave-Resolving Drifters (or WRDs), are small, lightweight and inexpensive enough to be deployed and retrieved in large numbers from small vessels. To study wave evolution in the San Francisco Bight and the Mouth of the Columbia River, 30 WRDs are deployed during peak ebb tide so that the drifters flow into the incident wave field. Wave statistics estimated through local ensemble averaging of drifter observations and ensemble-averaged wave spectra are used to describe the wave evolution through the inlet area. The observations reveal dramatic spatial variability in the wave field and sometimes doubling of the local wave heights. Comparisons with numerical simulations of the SWAN (Simulating Waves Near Shore) model and geometric optics theory (ray diagrams) show the distinct effects of refraction by variable shoals and currents on the wave field and hint at nonlinear instabilities that may cause rogue wave development.
Type
Thesis
Description
Series/Report No
Department
Oceanography
Organization
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.