Infragravity Seiches in a Small Harbor

TitleInfragravity Seiches in a Small Harbor
Publication TypeJournal Article
Year of Publication2017
AuthorsCuomo G., Guza RT
JournalJournal of Waterway Port Coastal and Ocean Engineering
Volume143
Date Published2017/09
Type of ArticleArticle
ISBN Number0733-950X
Accession NumberWOS:000407089100024
KeywordsField measurements; Harbor resonance; hazard; infragravity waves; long waves; Seiches; tsunami
Abstract

A method is developed to estimate harbor seiche at Marina di Carrara, Italy, from the properties of wind-generated incident waves outside the harbor. A linear model of the spatial structure of amplified seiche modes is combined with empirical estimates of the response of each mode to variable incident wave forcing. These empirical coefficients parameterize the complex nonlinear transfer of energy from wind waves to lower frequency seiche. As at other small harbors (< 1 km(2) surface area) on ocean coasts, and consistent with previous analyses at Carrara, the observed seiche is relatively energetic at several periods between about 1 and 15 min that are highly amplified theoretically, and the spatial structure of modeled and observed seiches agree as well. The longest seiche (approximate to 15 min) mode is almost spatially uniform within the harbor and dominates with low-energy, short-period incident wind waves (measured 1 km offshore of the harbor). Increased wave energy and longer periods excite shorter period (1-3 min) seiche modes with more complex spatial structure, including small areas of high amplification, which have led to operational issues. The energy in each of the six most energetic seiche modes is related in this paper empirically to offshore incident wind wave height and peak period, allowing detailed predictions of harbor seiche from routine wind wave forecasts. The approach appears applicable to relatively small, shallow harbors with reflective quay walls, in which the exterior harbor mouth is exposed, and the interior sheltered from energetic wind-generated waves. (C) 2017 American Society of Civil Engineers.

DOI10.1061/(asce)ww.1943-5460.0000392
Student Publication: 
No
Research Topics: