Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Observation of infragravity waves in the Chancay Bay, Peru
Jian Zhou1, Peiliang Li2, Xin Xiao1, Jiwen Song3, Shengli Chen3
1CCCC Water Transportation Consultants Co., Ltd., Beijing, China
2

Ocean College, Zhejiang University, Zhoushan, Zhejiang, China

3Marine Information Technology Center, CNOOC Information Technology Co., Ltd, Beijing, China

options in Geralton Port (Johnson and McComb, 2011; Mortensen et al.,2014). Troch et al. (2021) used Delft3D-Surfbeat to model IG wave
propagation into the Port of Cape Town and developed a long wave
forecasting system. Sheikh and Ewans (2015) applied Ideal Surf Beat(IDSB) model for IG wave simulation and the estimation of IG design
criteria at the Barrow Island LNG Jetty export berth. SWASH (Alavantas,2015; Rijnsdorp, 2012) and Xbeach(Daly, 2011) are also available tosimulate IG wave processes.

ABSTRACTThis study analyzed the characteristics of infragravity (hereafter IG)
waves based on field observation collected in the Chancay bay, Peru. The
results of the SUV method show that IG wave heights and periods werein the range of 0.04-0.34m (mean value of 0.12m) and 69.0-154.9s (meanvalue of 97.5s), respectively. Most of large IG waves closely related tohigh swell waves appear at 190-315°. With the bispectral method, it isfound that the bound wave energy only contributed a small amount (atmost 10%) of the observed IG wave energy at 25 m depth. Edge wave isthe main component of IG waves. An empirical formula to estimate IG
wave heights is developed, based on the local swell waves properties.

Due to strong correlations between IG waves and short waves (or swellwaves), empirical formulas based on short wave parameters weredeveloped to predict IG wave heights (Nelson et al., 1988; Bowers, 1992;
Lara et al., 2004; McComb et al., 2005; Thiebaut et al, 2013; Ardhuin etal., 2014). The empirical formula is generally developed based on therelationship between IG wave heights and measured short wave heights,
wave periods or spectral parameters.

KEY WORDS: Infragravity waves; bound waves; free long waves;
SUV method; bispectra analysis.

IG waves can also cause mooring problems in some ports, such as
Salalah Port (Van der Molen et al., 2019), Geraldton Port (Van der Molen,2014), Esperance Port (Bhautoo, 2017), Taranaki Port (Johnson andMcComb, 2011), Torsminde Harbour (Kofoed-Hanse et al., 2005), andTomakomai Port (Van Der Molen et al., 2006).

INTRODUCTION
Infragravity (hereafter IG) waves play an important role in nearshore
dynamic processes and ship motions in the port. The generation of IGwaves is closely related to wave group and breaking (Longuet-Higginsand Stewart, 1962; Symonds et al., 1982; Schäffer, 1993). Many studies
found that the nearshore IG waves were combinations of bound longwaves and free long waves (edge wave and leaky wave) (Huntley et al.,
1981; Elgar et al., 1992; Okihiro et al., 1992; Herbers et al., 1994;
Ruessink, 1998; Mendes et al., 2020; Rijnsdorp et al., 2021). Bispectral
analysis was generally used to identify bound waves. A comprehensive
review on IG waves from driving mechanisms to impacts can be foundin Bertin et al. (2018).

A multi-purpose terminal is planned to be built in the Chancay Bay. In
order to assess the potential risk of IG waves to port operations, an ADCP
was deployed in the Chancay Bay. In this study, IG wave characteristics
are investigated using the SUV method and bispectal analysis. Also, anempirical formula is developed to estimate IG wave heights. The
conclusions of this paper can provide useful information for verificationof IG wave modeling and dynamic mooring analysis for port planninglayout.

Numerical models were also used to investigate IG waves. The
Boussinesq-type models (Funwave model and MIKE 21 BW model)
were undertaken to simulate IG waves and analyze potential mitigation

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