Wave Evolution in River Mouths and Tidal Inlets
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2014
- Accession Number
- ADA607721
Entities
People
- Douglas W. Pearman
Organizations
- Naval Postgraduate School