Peak Wave Period Research Articles

Real-time inverse estimation of multi-directional random waves from vessel-motion sensors using Kalman filter

The real-time inverse estimation of the ocean wave spectra and elevation from a vessel-motion sensor is highly valuable, although it is still in the early stages of development. The Kalman filter method using motion measurements has advantages over other methods in terms of real-time capability, cost savings, and easy installation. In this paper, the Kalman filter method is developed for the inverse estimation of multi-directional waves in real time. The problematic divergence in the high-frequency region encountered by previous papers using similar approaches is resolved by employing the Wiener filter method. The developed method is also shown to be robust against potential sensor noises. The real-time multidirectional-wave spectrum and elevations can be recovered, including the high-frequency region, using the developed methodology with the numerically generated motion-sensor signals with noise. The developed Kalman filter algorithm is tested and validated for various sea states of uni- and multi-directional waves. The inverse estimation of multi-directional waves is generally less accurate compared to that of unidirectional waves, mainly due to the significant increase of unknowns (component waves) in the Kalman filter processes. Nevertheless, the overall wave spectra, elevation time series, significant wave heights, peak period, main direction, and directional spreading were well recovered.

Experimental uncertainty analysis of monopile scour protection stability tests

Hydraulic experiments using physical scale models of monopile scour protections typically have high experimental uncertainties and data scattering. These uncertainties may severely affect the accuracy of the experimental results and need to be analysed quantitatively. This paper presents a study on the quantification of experimental uncertainties in monopile scour protection damage tests following the Guide to the expression of Uncertainty in Measurement (GUM) (ISO, 2008). The uncertainty analysis is performed using the three-dimensional damage number S3D and the widely applied STAB number. Through the analysis of the S3D number from individual test and repeated tests, it is found that the uncertainty analysis method for an individual test can be efficiently applied to predict the experimental uncertainty. The wave peak period and the current velocity are identified as the two major sources of uncertainties for the S3D number. The flow turbulence and correlations between input parameters can be neglected when estimating the uncertainty. The uncertainty analysis of the STAB number shows that the experimental uncertainty due to measurement can be up to 5% to 7% of the obtained STAB result. This uncertainty range is wide in comparison with the narrow margin of a dynamic scour protection design in DNV’s recent recommended practice (DNV-RP-0618). The uncertainty of the STAB number is more affected by the armour stone density, wave peak period and significant wave height.

Shape investigation and probabilistic representation of coastal storms. Applications to Mykonos and Barcelona

The main objective of the present work is the probabilistic representation of coastal storms’ parameters through non-parametric probability distributions that can give satisfactory estimates in the whole range of the variables’ values. Their proper probabilistic representation can provide crucial information for many applications including the probabilistic design of marine and coastal structures. Different non-parametric univariate distributions in combination with different copula types or the conditional model are applied, to check the closeness of their fit to the available bivariate coastal storm data (e.g., the storms’ maximum wave height and the associated peak wave period). Moreover, except for the classical kernel distribution, a new, recently developed Box-Cox transformed kernel method is also examined and applied. The latter has been already evaluated so far to sea states data but not to storm data. Therefore, the adopted methodology is implemented to real coastal storms in two different locations, derived from wave recordings from Mykonos (Greece) and Barcelona (Spain). Furthermore, some of the significant statistical properties of the observed coastal storms, such as the calm period, the duration, and the shape (triangular or trapezoid) are also detected. From the present analysis, the derived methodology for representing accurately coastal storms is clarified, giving thus a useful tool to engineers and researchers to consider extreme events probability of occurrence, which is essential for the design of coastal structures and consequently for the protection of coastal communities.

Wave–Tide Interaction for a Strongly Modulated Wave Field

Abstract Observations from Coastal Data Information Program (CDIP) moored buoys off the coast of Florida reveal tidally driven wave–current interactions that modify significant wave heights by up to 25% and shift peak periods by up to a second. A case study at Fernandina Beach, Florida, shows surface waves steepening on following tidal currents and becoming less steep on opposing tidal currents, with the largest modulations occurring in the long-period swell band. To better understand tidal modulations as a function of the phase of the tide, we use simplified analytical and numerical solutions to the equations of geometrical optics and conservation of wave action under the assumption of a one-dimensional tide acting as a progressive shallow-water wave. The theoretical frameworks allow us to identify parameters that characterize the magnitude of variation in surface waves due to tidally induced currents and changes in water depth. We compute modulations to the omnidirectional and directional wave spectrum (between 0.05 and 0.15 Hz), as well as characteristic bulk parameters such as significant wave height and peak period. The theory is corroborated using directional wave and surface current observations from the Fernandina Beach CDIP station (located in water of average depth of 16 m). We find that the numerical results reproduce the observed wave modulations due to tidal currents and changes in water depth. Specifically, surface waves traveling in the direction of the tide are strongly modulated, and the relative speeds between the tide and surface waves set the sign and magnitude of these modulations. Given knowledge of tidal currents, water-depth variations, and wave climatology, theoretical and numerical predictions may be used to provide both statistical and instantaneous estimates of wave-height variations due to tides. Because operational forecasts and nowcasts do not routinely include tides or currents, these findings can help to accurately represent nearshore surface wave variability.

Spectral wave modeling of bimodal sea states at laboratory and coastal scales

A downshift of the wind wave peak frequency was observed in a wind wave tunnel when irregular long paddle-waves (i.e. generated mechanically with a plane wave-maker) are added in the sea state. The 3rd generation spectral wave model, TOMAWAC, is used to assess the extent at which this peak frequency downshift can take place at prototype scale in bimodal sea-state conditions involving swell and wind wave systems. Several parameterizations of the modeled physical processes are selected to numerically reproduce the laboratory experiments in the first place. Then, the model performances are further inquired in reproducing coastal observations during a specific event combining a wind wave and a swell system. Overall, a good agreement is obtained between the simulations and the observations both at laboratory and coastal scale. In particular, a set of parameterizations combining one of the latest developments in spectral wave models for the whitecapping dissipation and the nonlinear 4-wave interactions reveals high performances in reproducing the observations. Lastly, based on the performances of this latter set of parameterizations, a generic numerical domain with typical coastal scale dimensions is created to inquire the occurrence of the downshift at prototype scale. This last study reveals a wind wave peak period shift from 5 s without swell to more than 6.5 s with a 2 m high swell.

Load Evaluation for Tower Design of Large Floating Offshore Wind Turbine System According to Wave Conditions

This study entailed a load evaluation for the tower design of a large floating offshore wind turbine system in accordance with the wave conditions. The target model includes the IEA 15 MW reference wind turbine and a semi-submersible VolturnUS-S reference floating offshore wind turbine platform from the University of Maine. The OpenFAST, which is an aero-hydro-servo-elastic fully coupled analysis tool, was used for load analysis. The DLC1.2 and 1.6 were used as the design load cases, and the environmental conditions suitable for the design load cases were cited in the VolturnUS-S platform report. Load evaluation was performed according to time series and FFT results. The findings of the study are as follows: first, in the correlation analysis, the tower-top deflection had the highest correlation, and this further affects nacelle acceleration. Second, the tower-base pitch moment increased with the significant wave height. However, the wave peak period increased until it matched the tower-top deflection frequency and decreased thereafter. Third, the comparison between the normal and severe sea state conditions revealed that the tower-base pitch moments for the two conditions are almost similar, despite the conditions wherein the wave spectral energy differs by a factor of 3.5. Fourth, the tower shape is changed while adjusting the diameter of the tower, and the tower-top and tower-base pitch moments are reviewed using a redesigned tower. Even if the mass is the same, adjusting the diameter of the tower reduces only the pitch moment.

Increasing trends in spectral peak energy and period in a semi-closed sea

This study aims to investigate long-term trends in the Black Sea's spectral wave peak energy and periods. Improved Visualization of the Innovative Trend Analysis and the Mann-Kendal methods was applied to the maximum and mean spectral peak energies and peak periods between 1979 and 2020. Long-term spectral data are obtained from the ERA5 reanalysis and two spectral wave models, SWAN and WWIII. The innovative trend analysis method has the particularity to examine trends in higher and lower value categories. Studies of long-term changes in spectral wave characteristics are rare, and trends in spectral peak parameters are evaluated in this study for the first time in the Black Sea. It was detected that both spectral peak energies and peak periods tend to increase predominantly over most of the time scales. Furthermore, while the change rates for peak energies do not exceed 40% annually and seasonally, change rates exceeding 100% are observed on a monthly basis. Besides, the change rates of the peak periods vary in the ±5% band and usually do not exceed 15%. Moreover, despite a few differences, trend analysis results obtained using SWAN and WWIII models were close to the global ERA5 results. The results may provide insight into the design and durable development of coastal and marine structures as well as the evaluation of wave climate change based on spectral wave data.

Directional effects of correlated wind and waves on the dynamic response of long-span sea-crossing bridges

Sea-crossing bridges are sensitive to wind and wave loads, different wind and wave loading directions will lead to significant differences in bridge dynamic performance. The design of such a structure may benefit from considering the directional characteristics of loading. This study thus proposes a directional wind-wave-bridge (DWWB) numerical framework by incorporating multivariate statistical dependence, directionality analysis, and a wind-wave-bridge system for sea-crossing bridges. The trivariate joint probability distribution is first simulated by an optimized C-vine copula, and the correlated wind and wave combinations are identified by the 3D environmental contours based on the measured data in the bridge site. Directionality analysis involving the alignment and misalignment of wind and waves are further investigated. The proposed approach is finally applied to a real sea-crossing bridge with the mean wind speed, significant wave height, peak wave period, wind direction, and wave direction as the input variables of DWWB. The nonlinear dynamic response as the output is solved by equilibrium iterations using the Newmark-β method. The results show that the occurrence probability of wind–wave misalignment is up to 50%. The dynamic response of the bridge is sensitive to the wind and wave direction. Neglecting the multivariate statistical dependence and directional effect of wind and waves may lead to a conservative and unrealistic result.

Beach-cast appearance on the tide-less sea shore: Parameters of favoring surface waves

The beach-cast material attracts more attention nowadays since it contains both organic wrack, considered as a natural resource, and plastic waste which is potentially dangerous for biota. The material resides on the beach for a short time, making the prediction of the beach-cast event important. With the idea to disclose hydrodynamics behind the appearance of these hazardous patches on the seashore, the likelihood methods were applied to the freely available surface-waves reanalysis data and the observations of beach-cast appearance on the northern shore of the Sambian peninsula (south-eastern part of the Baltic Sea) in 2011–2021. Significant wave height, peak wave period, and mean wave direction at the open-sea limit of the coastal zone were analyzed with the differentiation between the “freshly discovered” and “ordinary” beach-casts. The results were refined using different time-frames of sampling of surface-wave parameters and indicated the 3-day period as most suitable for the present analysis. The most important parameters for beach-cast appearance are large wave heights (>4 m) and long periods (>6 s) in the preceding period. Waves from the northern sector are especially favorable: they have the largest possible fetch for the region, and the studied shore is directly exposed to them. This suggests that a fully developed wave field after a storm with a long wave fetch is an essential condition for the appearance of a beach-cast. Wave periods and heights are interchangeable when analyzing the sea state before the beach-cast appearance. The results are in agreement with both present-day and long-term historical observations.

Numerical Investigation on Hydrodynamic Processes of Extreme Wave Groups on Fringing Reef

The low-lying reef islands distributed in the tropical and subtropical coastal regions are highly vulnerable to the devastating damages of surges and waves during the severe weather events. Over the past two decades, extreme waves have caused tremendous loss and damages to the tropical and subtropical coastal regions. Previous research has focused on the wave hydrodynamics of tsunami waves, as well as regular and irregular waves on the fringing reefs. The complex wave hydrodynamics of extreme waves on the fringing reefs are rarely studied. By applying the nonhydrostatic numerical flow solver (NHWAVE), transformation and breaking process of the crest- and trough-focused wave groups on the fringing reef are analyzed in this study. Influences of the major factors, i.e., water depth, significant wave height, peak wave period, forereef slope and backreef slope, and ridge width, are discussed in detail. The results show that there are complex interactions between the fringing reef and the focused wave group. Breaking waves of high intensity can form at the reef crest. Meanwhile, due to the wave breakings at the reef crest and bottom friction of the reef flat, the local wave height can be effectively reduced. Within the complex wave hydrodynamics of focused waves on the fringing reef, most of the wave energy can be dissipated. In addition, hydrodynamic difference between the crest- and trough-focused waves on the fringing reef is very limited. The research results of this study will further help researchers to better understand the wave hydrodynamics of extreme waves over the fringing reefs.

Theoretical evaluation of the power efficiency of a moored hybrid floating platform for wind and wave energy production in the Greek seas

<abstract> <p>In this study, an extreme value analysis of wind and wave parameters is presented for three specific locations in the Greek seas that are known to be advantageous in terms of joint power production (both offshore wind and wave) and bathymetric conditions. The analysis is conducted via the Peak-Over-Threshold method, examining wind speed, significant wave height and peak wave period data from the ERA5 reanalysis dataset. Moreover, a multi-purpose floating platform suitable for offshore energy production is presented, which combines wind and wave energy resources exploitation and can be adequately utilized at the selected locations. The analysis is built to incorporate the solutions of the diffraction, motion-dependent and pressure-dependent radiation problems around the floating structure, along with the mooring line and wind turbine (WT) characteristics. Subsequently, a coupled hydro-aero-elastic analysis was performed in the frequency domain, while a dynamic analysis was conducted in order to evaluate the mooring characteristics. Lastly, offshore wind output and absorbed wave energy values were estimated, and different types of mooring systems were compared in terms of efficiency. It has been concluded that the wind energy capacity factor is higher than 50% in all the examined locations, and by the mooring system comparison, the tension-leg platform (TLP) represents the best-case scenario for wave energy absorption.</p> </abstract>

Optimal Estimation of the Peak Wave Period using Smoothing Method

In this study, a smoothing method was applied to improve the accuracy of peak wave period estimation using the water surface elevation observed from the Oceanographic and Meteorological Observation Tower located on the west coast of the Korean Peninsula. Validation of the application of the smoothing method was performed using variance of the surface elevation and total amount wave energy, and then the effect on the application of smoothing was analyzed. As a result of the analysis, the correlation coefficient between variance of the surface elevation and total amount wave energy was 0.9994, confirming that there was no problem in applying the method. Thereafter, as a result of reviewing the effect of smoothing, it was found to be reduced by about 4 times compared to the confidence interval of the existing estimated spectrum, confirming that the accuracy of the estimated peak wave period was improved. It was found that there was a statistically significant difference in probability density between 4 and 6 seconds due to the smoothing application. In addition, for optimal smoothing, the appropriate number of smoothings according to the significant wave height range was calculated using a statistical technique, and the number of smoothings was found to increase due to the unstable spectral shape as the significant wave height decreased.

Numerical Analysis on Influences of Emergent Vegetation Patch on Runup Processes of Focused Wave Groups

During severe weather, the runup of the devasting surges and waves can cause extensive damages to the coastal facilities and results in significant loss of life. Therefore, it becomes necessary to find reliable measures to reduce the wave runup in coastal regions. As a natural barrier to the shorelines, coastal vegetation has great potential to attenuate wave runup and to prevent the coastal communities from extreme floodings and huge land loss. This study numerically discusses the influences of the emergent vegetation patch on the runup processes of extreme wave groups by applying a nonhydrostatic flow solver. Influences of the major factors, i.e., water depth, peak wave period, significant wave height, and density and length of the vegetation patch, are analyzed in detail. Research findings indicate that the presence of the emergent vegetation patch can substantially dissipate most of the incident wave energy and effectively reduce the maximum wave runup heights of extreme wave groups at the sloped beach. It is hoped that the research results of this study will be helpful to the design of coastal soft protection measures.

Efficiency and Wave Run-Up of Porous Breakwater with Sloping Deck

In order to protect fragile shoreline and coastal assets during extreme storms, a combined floating breakwater-windbreak has been proposed to reduce both wind and wave energies in the sheltered area. The 1 km-long breakwater has a porous hull with internal tubes to allow free passage of water; thereby further dissipating wave energy. The deck of the structure is designed to have a slope of 25 degrees facing the upstream side, and arrays of cylindrical tubes are placed on the sloping deck to form a windbreak. A reduced-scale (1:50) model test was carried out in a wave flume to examine wave sheltering performance under significant wave heights Hs = 3.0 m to 7.5 m and peak wave periods Tp = 9.4 s to 14 s sea states. Both regular and random wave conditions with different wave heights were considered. It is found that transmission coefficients ranging from 0.4 to 0.6 can be achieved under tested wave conditions. Porous breakwater hull increases the wave dissipation coefficients and is effective in reducing the wave reflection at the upstream side. The wave run-up length is dependent on the Iribarren number if the reduction induced by vertical freeboard is considered. Based on experimental data, empirical formulae have been proposed to predict the wave run-up responses in regular waves, probability of non-zero wave run-up occurrence, modified Weibull distribution of the wave run-up peaks and extreme wave run-up in random waves.

Low-cost investigation of wave dynamics across low energy reef environments in Indonesia

The interaction between offshore waves and complex reef bottom profiles determines the hydrodynamic processes within the reef beaches, for instance, Sea-Swell (SS) wave dissipation, Infragravity (IG) wave generation as well as wave-induced currents and setups. These hydrodynamics phenomena are important to several ecological processes and control the associated shoreline erosion and flooding. Hence, a good understanding of the dynamics is needed that wave observations are challenging and expensive otherwise. Here we present a short term (12 hours) investigation of non-directional spectral waves using a series of HOBO pressure sensors. Six pressure sensors were deployed at 3 locations along the fringing reefs of Tunda Island, Banten Province - Indonesia. The wave spectra were estimated from the surface water fluctuations using linear wave theory for each hourly burst data. During observation, the Tunda waters were calm with significant wave heights were less than 10 cm with peak wave periods of ∼12 s at all sites. Despite the short period measurement due to memory issue, the result demonstrated the ability of HOBO pressure sensors to measure non-directional wave spectra at shallow water.

Investigation of Waves Generated by Tropical Cyclone Kyarr in the Arabian Sea: An Application of ERA5 Reanalysis Wind Data

In this study, the wave conditions in the Arabian Sea induced by tropical cyclone Kyarr (2019) have been simulated by employing the 3rd generation wave model MIKE 21 SW. The model was run from 24 October to 1 November 2019, a total of 8 days. The MIKE 21 SW model was forced by reanalyzed ERA5 wind data from the European Centre for Medium-Range Weather Forecasts (ECMWF). The results are compared with buoy data from the Indian National Centre for Ocean Information Services (INCOIS), which is located at 67.44° E, 18.50° N. In addition, the satellite altimeter data (CryoSat-2, SARAL and Jason-3 satellite altimeter data) was utilized for validation. Three wave parameters are considered for the validation: the significant wave height; the peak wave period; and the mean wave direction. The validation results showed that the significant wave height, the peak wave period, and the mean wave direction could be reasonably predicted by the model with reanalysis wind data as input. The maximum significant wave height reached to 10.7 m (with an associated peak wave period of 12.5 s) on 28 October 2019 at 23:00:00 in the middle of the Arabian Sea. For coastal areas, the significant wave height along the Iran and Pakistan (north Arabian Sea) coasts increased to a range of 1.4–2.8 m when tropical cyclone Kyarr moved northward. This wave height along with elevated sea level may cause severe coastal erosion and nearshore inland flooding. Impacts of cyclones on coastal zones critical facilities and infrastructure can be reduced by timely and suitable action before the event, so coastal managers should understand the effect of cyclones and their destructive consequences. The validated model developed in this study may be utilized as input data of evaluating the risk to life and infrastructure in this area.

Nearshore Wave Energy Resource Assessment for Off-Grid Islands: A Case Study in Cuyo Island, Palawan, Philippines

Electrifying off-grid and isolated islands in the Philippines remains one of the challenges that hinders community development, and one of the solutions seen to ensure energy security, energy access and promote a low-carbon future is the use of renewable energy sources. This study determines the nearshore wave energy resource during monsoon seasons in Cuyo Island using a 40-year wave hindcast and 8-year on-site wind speed data as inputs to develop a high-resolution wave energy model using SWAN and assesses its annual energy production through matching with wave energy devices. The results show that the average significant wave height (Hs), peak period (Tp) and wave power density (Pd) during a northeast monsoon are Hs = 1.35 m, Tp = 4.79 s and Pd = 4.05 kW/m, respectively, while a southwest monsoon, which is sheltered by the mainland, results in Hs = 0.52 m, Tp = 3.37 s and Pd = 0.34 kW/m. While the simulated model was observed to overestimate the significant wave height (bias = 0.398, RMSE = 0.54 and SI = 1.34), it has a strong relationship with the “observed values” (average r = 0.9). The annual energy production for Wave Dragon, Archimedes Wave Swing and Seawave Slot-Cone Generator are highest at 1970.6 MWh, 2462.04 MWh, 62.424 MWh and 4099.23 MWh, respectively.

Numerical analysis of wave climate driven variations in longshore sediment transport along Mahabalipuram coast, Southeast coast of India

The study examines the impact of wave climate change on the longshore sediment transport rate (LSTR) along Mahabalipuram (a UNESCO World Heritage Site) on the east coast of India. Wave climate changes and LSTR were evaluated using a spectral wave module (MIKE 21 SW) and LITPACK (1951–2020). The hourly integral wave parameters (significant wave height (Hs), peak wave period (Tp), and mean wave direction (Dm)) computed at the study location were used to estimate net and gross LSTR. The average Hs, Tp, and Dm were 0.85 m, 7.34 s, and 118° (E-SE), respectively, resulting in an average net northerly transport of about 0.046 × 106 m3/year, and gross transport of 0.2 × 106 m3/year. It has been shown that the changes in the LSTR are primarily associated with the LST of the seasonal variations that correspond to the seasonal changes in the wave climate. An overall increasing trend in wave climate (0.001 m/yr), net (∼ 320 m3/yr), and gross (∼ 619 m3/yr) LSTR was observed. The gross LSTR showed an increasing trend of about 17.6 % (1951–2020).The net LSTR is northward, except for a few years when the direction of net LST reversed. Understanding the variability in longshore sediment transport at the seasonal, inter-annual, and decadal scales is vital for designing better management plans for a coast.

Numerical Study on Hydrodynamics of Submerged Permeable Breakwater under Impacts of Focused Wave Groups Using a Nonhydrostatic Wave Model

Extreme waves, called rogue waves or freak waves, usually occur unexpectedly and with very large wave heights. In recent years, extreme waves were reported not only in deep ocean waters but also in shallow waters, which threaten the safety and intactness of the coastal regions. To prevent the coastal infrastructures and communities from the devastating power of extreme surges and waves, many coastal defense structures were built along the coastline, i.e., submerged permeable breakwaters. However, the number of studies on the hydrodynamic characteristics of a submerged permeable breakwater under the impact of extreme waves is relatively few. In addition, wave focusing has been widely used to generate extreme waves in the past few decades. Hence, as a necessary supplement to the previous research work, the hydrodynamic performance of a submerged permeable breakwater under the impacts of focused wave groups was numerically studied by using a nonhydrostatic numerical wave model (NHWAVE). The influences of several main factors, such as the incident significant wave height, water depth, wave peak period, porosity of the breakwater (n), and the side slope angle of the breakwater, were considered. It is expected that the results of this study will further strengthen the research on the hydrodynamic characteristics of a submerged permeable breakwater under extreme wave conditions.

Modelling and simulation of extreme wave heights around agatti island of lakshadweep, west coast of India

Small islands experience variation in wave energy regime along shorter shoreline due to refraction, diffraction and variability in direction of wave travel. Nearshore wave climate around these islands is quite complex due to wave transformation associated with configuration of islands, and high steepness in the bathymetry. Understanding wave energy will help in identifying suitable locations for coastal structures, wave energy devices and sediment budgeting. Assessment of extreme wave climate around the islands play a crucial role in the design and survival of coastal infrastructure for any developmental activities in islands. This study investigates the extreme wave climate around the Agatti island of Union Territory of Lakshadweep located in west coast of India. The spatial variability of wave power distribution around the Agatti island is analyzed based on 10 years of wave hindcast data from spectral wave modelling for the period between 2011 and 2020 using spectral wave model. In this study, third-generation spectral wave model was used to simulate the wave climate over the Arabian Sea. Regional model was established using ECMWF model winds and the offshore wave parameters were validated with deep water ocean observations AD07 and AD09 deployed in the Arabian Sea. To understand the nearshore wave transformation along the Agatti island, local wave model of fine resolution was established using high resolution bathymetry and is validated using the coastal buoy (CB02) deployed near Agatti. Nearshore wave parameters such as Significant wave height, Peak wave period (Tp) and Mean wave direction (θm) were analyzed. The wave power distribution around the island was quantified and demarcated for siting of offshore structures for developmental activities. The study reveals that the south zone of the island is more energetic with annual mean wave power of 8–12 kW/m and during monsoon, wave power more than 28 kW/m is observed. The extreme value theory based on Generalized Extreme Value distribution is applied to the extreme wave height estimate based on modelled wave data around the Agatti island. The extreme wave heights for different return periods were estimated around the Agatti island for design and analysis of coastal infrastructure.