Variation Of Wave Height Research Articles

Spatial and temporal variation of nearshore significant wave height in the Three Gorges Reservoir, China

The study of wave characteristic changes is critical for understanding the role of wave erosion in the shoreline erosion of reservoirs and its subsequent impact on environmental pollution. This study utilizes RBRvirtuoso D-wave-pressure-based wave gauges to make in situ observations of the nearshore significant wave height (SWH) in the Three Gorges Reservoir. The differential and impact factors affecting the SWH under varying water levels, in the main and tributary streams, and shoreline sections are analyzed. This research also investigates the alteration of the frequency distribution of the SWH. The findings indicate that the average SWH increases as the water level increases, reaching 1.2 cm, 1.5 cm, and 1.9 cm for water levels of 150 m, 165 m, and 175 m, respectively, with a SWH frequency distribution curve that becomes increasingly smooth. The average SWH in the mainstream is 2.9 times larger than that in the tributaries, with the former having a smoother frequency distribution curve. The average SWHs in different shoreline sections are inconsistent at the same water level, with the Badong (downstream) section near the Three Gorges Dam exhibiting a significantly higher average SWH than the Zhongxian (midstream) section further from the dam. When shipping activities intensify, there is often a marked increase in the magnitude of the SWH. The SWH in narrower reservoir sections is significantly greater than that in wider sections, with average measurements of 2.2 cm and 1.4 cm, respectively. Fluctuations of the water level, shipping activities, and other factors in the Three Gorges Reservoir have a significant impact on the alteration of the nearshore SWH, and changes in the SWH from low to high water levels may result in changes in both the spatial and temporal patterns of shoreline erosion. These alterations can, in turn, affect sediment and nutrient transport, potentially exacerbating environmental pollution issues.

Developing a Resilience Index for the Pile-Supported Piers of the Port of Batangas under Tsunami Load

The roll-on/roll-off (ro-ro) transport system, which plays a huge role in the transportation and economy of the Philippines, mainly uses piers to provide smooth berthing of ships. However, its structural configuration attracts different hazards causing damage, particularly to piles. Tsunamis produce devastating wave forces. This may heavily result in discontinuity of the whole port operation as there will be no available berthing structure for ships. Hence, this study was conducted to determine the structural resilience of the pile-supported piers of the Port of Batangas against tsunami loads at different variations of wave height and water depth. Structural software was used to model the piers and incorporate calculated tsunami drag forces. Furthermore, pushover analysis was performed to produce the base shear versus displacement curves needed for the calculation of the robustness index. The rapidity index, on one hand, is based on an interview with the Philippine Ports Authority - Port Management Office (PPA-PMO) of Batangas resulting in recovery rates for demolition works and pile replacement. Combining these indices using the concept of resilience triangle, values of the resilience index ranging from 0.0 to 1.0 were calculated at both longitudinal and transverse directions. As a result, the piers were categorized as highly resilient in almost 50% of the tsunami load cases. It proved that the pier with existing batter piles exhibits higher resilience than the other which is only supported by vertical piles.

Fatigue Life Analysis on The Local Construction Near the Chain Stopper Area of Papa Terminal Floating Storage Offloading (FSO) With 4X2 Chain Line Spread Mooring Configuration

This research aims to determine the fatigue life of the structure near the chain stopper of a storage tanker using the spectral fatigue analysis method. The wave spectrum is developed based on six significant wave height and period variations from the site wave scatter data using a modified spectrum of JONSWAP. The stress analysis is carried out using finite element analysis software. It can then be processed into Stress RAO from each loading direction. The response spectra are generated from the wave spectrum, multiplying with the square of the Stress RAO. These response spectra will determine the stochastic values of each stress range variation in obtaining the number of cycles that occur in each variation (nL). The accumulation of each ratio obtained from all existing variations will produce a fatigue index value (D). The American Bureau of Shipping’s S-N curve D-Class is used in this fatigue life analysis. The Gamkonora Aframax tanker operated as a temporary storage tanker at Papa’s field area is used as the case of this study.

Analysis of Spatial and Temporal Criteria for Altimeter Collocation of Significant Wave Height and Wind Speed Data in Deep Waters

This paper investigates the spatial and temporal variability of significant wave height (Hs) and wind speed (U10) using altimeter data from the Australian Ocean Data Network (AODN) and buoy data from the National Data Buoy Center (NDBC). The main goal is to evaluate spatial and temporal criteria for collocating altimeter data to fixed-point positions and to provide practical guidance on altimeter collocation in deep waters. The results show that a temporal criterion of 30 min and a spatial criterion between 25 km and 50 km produce the best results for altimeter collocation, in close agreement with buoy data. Applying a 25 km criterion leads to slightly better error metrics but at the cost of fewer matchups, whereas using 50 km augments the resulting collocated dataset while keeping the differences to buoy measurements very low. Furthermore, the study demonstrates that using the single closest altimeter record to the buoy position leads to worse results compared to the collocation method based on temporal and spatial averaging. The final validation of altimeter data against buoy observations shows an RMSD of 0.21 m, scatter index of 0.09, and correlation coefficient of 0.98 for Hs, confirming the optimal choice of temporal and spatial criteria employed and the high quality of the calibrated AODN altimeter dataset.

A numerical study on mitigation of sloshing in a rectangular tank using floating foams

In this paper, the feasibility of using floating foams as a mitigation device to suppress water sloshing in a rectangular tank is numerically investigated. The sloshing in the tank is initiated using a harmonic excitation. To perform 3D numerical simulations, the Arbitrary Lagrangian-Eulerian technique (ALE) in the commercial software ABAQUS is utilized. The results of the model are validated by comparing the results of simulations with those of the experiments both quantitatively and qualitatively. Next, the efficacy of floating foams in suppressing water sloshing is evaluated for different cases with various layers of foam ranging from zero to three layers. In addition, the effects of various parameters on the wave height and kinetic energy variations are comprehensively analyzed. These parameters include water depth, density, friction factor, diameter of plastic foam spheres, frequency, amplitude and type of excitation. The numerical results show that the interactions between floating foams play a major role in mitigating water sloshing. Furthermore, the effects of plastic foam densities on decreasing the wave height are minor. A twofold increase in the foam density decreases the maximum kinetic energy by 9.68% and an almost threefold increase in the foam density reduces the maximum kinetic energy by 29.03%.

Shoreline Temporal Variability Inferred from Satellite Images at Mar del Plata, Argentina

Sandy beaches are fragile and dynamic coastal areas exposed to numerous environmental forcings. Systematic long-term data acquisition programs and exhaustive data series analyses are fundamental for a comprehensive understanding of the coastal processes. The software CoastSat was implemented to detect the shoreline position at beaches located to the south of Mar del Plata city (Buenos Aires Province, Argentina), by means of satellite images (period: 1986–2020). Tides in this area are mixed semidiurnal with a mean range of 1.74 m. The most frequent waves are characterized by significant wave heights from 0.5 to 2 m and periods of around 8 s propagating mainly from SSE. Seasonal and interannual variability and long-term trends of the shoreline position were investigated at Punta Mogotes (PM) bay, Faro Norte (FN) bay, and Ensenada Mogotes (EM). Seasonal cycles were noticed in the beach width variation series. In general, maximum accumulation was observed in summer and maximum erosion in winter. Exceptions were appreciated at southern PM bay (maximum accretion in autumn and maximum erosion in spring) and at FN bay (beach rotation on a seasonal scale). The drivers of seasonal variation are likely seasonal variations in the significant wave height and direction. PM bay showed a strong interannual variability with a clear alternating pattern between the northern and southern sectors of the bay, in an 8 ± 1.2 years period. Long-term trends showed a generalized erosion along 9 of the 12 km of the analyzed coast.

On the role of wave climate temporal variability in bias correction of GCM-RCM wave simulations

This work presents the performance analysis of a multi-model ensemble of wave climate projections in the Mediterranean Sea against hindcast data. The wave projections were developed with the numerical model Wavewatch III forced by surface wind fields of 17 EURO-CORDEX GCM-RCMs providing time series of the main wave parameters on a 3-h and 10-km resolution. The performance of the wave GCM-RCM simulations during the baseline period (1979–2005) was assessed by means of the deterministic metrics RMSE and Bias. Different bias correction methodologies were analyzed by means of the application of the widespread Empirical Quantile Mapping method considering different time periods of significant wave height in order to analyze the ability of the bias-correcting methods to capture the different wave climate temporal scales ranging from storm events, monthly, seasonal and interannual variability. The results show that the use of the EQM method for the full-time series without taking into account other timescales, can lead to increased biases in some regions and seasons and that the use of time-dependent bias-correction techniques leads to an improved accurate characterization of biases considering the interannual temporal variability of significant wave height. More specifically the use of the EQM method for monthly data provides a good performance in capturing the correlation and interannual temporal variability of wave climate.

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.

Spatial and Temporal Variability of Significant Wave Height and Wave Direction in the Yellow Sea and East China Sea

Spatial and Temporal Variability of Significant Wave Height and Wave Direction in the Yellow Sea and East China Sea

Wave and storm surge evolutions in the Pearl River Estuary with large-scale land reclamation impacts

Globally, many estuarine areas are suffering from large-scale land reclamations to fulfill the land demands of city expansion. Understanding the wave and storm surge evolutions in response to human reclamations in estuaries is of vital importance regarding estuarine management (e.g., reclamation plan formulation, flood mitigation). The wave and storm characteristics, and their responses to 1990–2020 land reclamations in the Pearl River Estuary (PRE) were investigated by a storm surge model. Besides, the impacts of increasing typhoon intensity (TI) on the changes of waves and storm surges caused by reclamations were also illustrated under the background of global warming. Simulated results show that reclamations cause apparent variations of wave height and storm surge fields in the PRE. The wave height and surge height also increase with the enhancement of TI, consequently influencing the wave height and surge height change rates caused by reclamations. Furthermore, the combined actions of land reclamation and increased TI conduct the most remarkable effects and bring the highest surge height compared with other scenarios. Particularly, the maximum wave height and surge height can reach 0.88–2.31 m and 2.71–3.77 m along the seawalls of Zhuhai, respectively, indicating more enormous seawall submersion and inland flooding.

Investigation on innovative pile head breakwater for coastal protection

Coastal erosion is a global concern that has been augmenting due to the natural evolution of beaches, human activities and sea-level rise. One of the eco-friendly shore protection methods is to dissipate the wave energy by constructing offshore breakwaters. Conical pile head breakwater (CPHB) is one of the eco-friendly innovative offshore structures consisting of closely spaced piles with an enlarged cross-sectional area (conical pile head) in the vicinity of the free surface. In the present study, perforations are incorporated over the conical pile head to achieve higher efficiency by promoting energy dissipation. The influence of the perforations on the performance characteristics, namely wave transmission (Kt), wave reflection (Kr) and energy dissipation (Kd) of the perforated CPHB is comprehensively investigated through physical model studies. The effect of perforations and their distribution around the pile head (Pa), percentage of perforation (P) and size of perforations (S/D) on the wave attenuation characteristics are evaluated to arrive at an optimum configuration. The study is carried out under monochromatic waves of varying wave height (0.06–0.16 m) and wave period (1.4–2 s) at different depths of water (0.35, 0.40 and 0.45 m). A minimum Kt of 0.58 associated with Kr of 0.26 and Kd of 0.78 is obtained with an optimum configuration of Pa = 50%, P = 19.2% and S/D = 0.25. The Kt of the proposed CPHB is about 19 to 35% lesser than that of the perforated hollow pile breakwater under matching test conditions. Overall, providing the perforations is found to be effective in enhancing the wave attenuation capability by up to 12.4%. Further, empirical equations are formulated and validated with the experimental data. The empirical equations estimate the Kt and Kr values accurately with a high coefficient of determination ( R2 ≥ 0.90).

Wave‐Current Coupling Effects on the Variation Modes of Pore Pressure Response in a Sandy Seabed: Physical Modeling and Explicit Approximations

AbstractPrevious flume observations on the response of pore pressure in the seabed induced by the combined wave‐current were mainly limited to relatively deep‐water waves with wavenumber times water depth approximately above 1.0. Meanwhile, existing theoretical solutions neglected the variation of wave height induced by wave‐current coupling effects, limiting the accuracy of the predictions. In this study, the combined wave‐current induced pore pressure response within a sandy seabed is physically modeled in a water flume. A wide range of wave‐current parameters is examined. The effects of wave period, water depth, and wave height with the superimposed following and opposing currents on the change of pore pressure are investigated. The present experiments identify two new particular modes of pore pressure changing under superimposed current on waves, that is, the transition mode and the opposing‐current enhancing mode, besides the well‐recognized following‐current enhancing mode. The specific modes are determined by a dimensionless parameter characterizing the value of wavenumber times water depth for waves in the absence of a current. Based on the conservation of mass, momentum, and energy flux, an explicit solution for the wave height under the wave‐current coupling effect is derived. With this updated wave height, an analytical solution for combined wave‐current induced pore pressure response is further proposed, which agrees with the measured data. Based on this solution, a general diagram for the current effect on the mudline pore pressure amplitude is proposed, which is applicable for both laboratory and field conditions. Finally, the physical mechanism in three variation modes is discussed.

Investigating wind direction influence on wind generated waves using Delft 3D for Gaza Strip Coast

Wind and water levels influence wave overtopping and consequent coastal flood threat, which is especially important in hyper-tidal bays where even modest variations in wave heights may be devastating if they coincide with high tides. The influence of wind and wave characteristics on wave propagation, as well as the sensitivity of significant wave height, are numerically investigated along the Gaza Strip's beachfront as an example. Wind waves with a high amplitude and short duration are susceptible to opposing winds, and their steepening effect varies throughout the bay shoreline, underlining the impact of shoreline geometry and bathymetry on wave hazard. The findings contribute to our existing knowledge of the complex interplay between wind and waves, as well as the crucial variables that maximize danger and hazard variability along the coastline. The findings of this study can assist port and harbor managers prevent financial losses due to downtime, influence sustainable coastal sea defense design, and better understand how wave danger may change in the future owing to shifting storm tracks. The findings can also be used to improve coastal infrastructure design and disaster response planning. Two scenarios were investigated with a wind direction of 330 and 30. It seems that when the wind direction is 330, it produces a higher Hs of 1.2 m and relatively larger wave return period with a range of 12-22 s and a higher wave energy dissipation of 220 N/Ms. In contrast, when the wind direction is 30, it produces a smaller HS of 1m with a short wave return period of 15-17s and smaller wave energy dissipation of 120 N/Ms. Overall, a wind direction of 30 has fewer occurring chances over the year but it seems to produce a destructive wave that are spread over the whole coast with a rapid return period.

Numerical Investigation of Ship Waves and Associated Hydrodynamics Over a Sloping Bed With a Non-Hydrostatic Model

Abstract The ship waves and related hydrodynamics over a sloping bed are investigated numerically in this paper, and we aim to clarify the characteristics of ship wave deformation and its hydrodynamic effects. Laboratory experiments are performed with a self-propelled ship model to produce various wave conditions over a sloping bed in the water flume, providing the datasets for validation works of numerical simulations. With the implementation of model sensitivity analysis, numerical calculations of ship-induced waves and flow velocities are completed using the non-hydrostatic model in XBeach and compared against experimental measurements. The results show that the model is not only able to calculate primary and secondary waves well, but also the ship-induced near-bed velocity when ship waves are prominent in the water flume. Further numerical investigations of ship wave transformation and associated hydrodynamic effects are conducted over a sloping bed under different ship speed conditions. The ship wave height and run-up variations along the cross-shore transect clearly indicate the wave energy dissipation due to breaking and bottom friction. The ship-induced flow velocities are found to be mainly contributed by the low-frequency primary waves in our numerical experiments.

Variability of the coastal currents, waves and wind surge along the shore of the South-Eastern Baltic (Kaliningrad Oblast, Russian Federation)

The coastline of the Kaliningrad Oblast is an area of the South-East Baltic, which continues from the Vistula Spit to the Curonian Spit via Sambia Peninsula. The coastline has been subject to severe erosion over the past years. The goal of the paper is to analyse whether the alongshore variations of the storm surge water level, field of waves and currents are the reason for the erosion alongshore variability. The numerical simulations were carried out using the quasi-stationary approach for the model wind. The offshore wave breaking distance and the non-linear dependence between wind surge and wind speed were estimated for four typical coastline sites. The alongshore velocity on most of the coastline was enough powerful to transport the fine, medium and coarse sands. West, northern-west and north winds were defined as the most dangerous for coastal erosion. The convergence and divergence of alongshore currents as well as the vortex zones were identified for each wind direction. The results were used to analyse the alongshore current velocity, wind surge, and significant wave height variability against the shore erosion characteristics. The hypothesis that the places of convergence and divergence of alongshore currents correspond to the accumulative and erosion zones was not confirmed with one exception on the western shore of the Sambia Peninsula. Three options were supposed to explain the absence of correlation between the monitoring results on coastal erosion and modelled hydrodynamic conditions: the studied shore has not had enough free sand to demonstrate the typical behaviour of dissipative shores; the erosion characteristics depend on the very local conditions which were not resolved by numerical model; the main erosion has happened at the short term event basis when waves reach the shore at the background of a general Baltic Sea high-water level and is not a result of the general alongshore distribution of waves, wave surge and current characteristics.

Analysis of Komen scheme in the SWAN model for the whitecapping dissipation during the tropical cyclone

The extreme wave during the tropical cyclone poses a great threat to the coastal and ocean engineering. In this study, this wave is simulated by the Simulating WAves Nearshore (SWAN) model in the Yellow Sea, the East China Sea and the northern South China Sea where tropical cyclones frequently occur. The simulation focuses on the whitecapping dissipation with the Komen scheme, which controls the dissipation through several key coefficients, such as two wave-steepness-dependent coefficients (Stpm and Powst) and two wave-number-dependent coefficients (Delta and Powk). By calculating statistical parameters and introducing a quantitative evaluation method (Technique for Order Preference by Similarity to Ideal Solution, TOPSIS), optimal selections of key coefficients in the Komen scheme are determined after identifying reasonable ranges of these coefficients. The simulated wave parameters of the calibrated model match the measured data well, demonstrating the reliability of the key coefficient combination in the Komen scheme. The underestimation of large significant wave heights is improved, with little variation of small significant wave heights, and the underestimation of wave periods is improved during the whole process of the tropical cyclone.

Global Climatology of Extratropical Cyclones From a New Tracking Approach and Associated Wave Heights From Satellite Radar Altimeter

AbstractExtratropical cyclones (ECs) produce comparable wave heights and hazardous sea states to those under hurricanes. With strong wind speeds and considerably larger diameters, the impact of ECs on the global wave climate is substantial. Because ECs occur more frequently, move more quickly, and exist in a large variety of sizes and shapes, these storms are not as well documented. Here, we present findings from a global EC tracking algorithm aimed at creating an EC database of wave producing storms. We focus on the major ocean basins of extratropical cyclone activity: The North Atlantic, North Pacific, and Southern Oceans. Our tracking algorithm uses mean sea level pressure fields from the European Centre for Medium‐Range Weather Forecasts (ECMWF) high resolution, advanced data assimilating, ERA5 reanalysis over the years 1979–2020. The 42 year‐long data set of thousands of cyclone tracks allows seasonal patterns and longer‐term trends of EC activity to be analyzed in these ocean regions. In addition, we employ 36 years of satellite radar altimeter‐derived significant wave height (Hs) data from 14 inter‐calibrated satellite missions to study the wave climate induced by the identified ECs in each basin. The resulting wave climatology compares well with previous results in the mid to high latitudes. We then analyze average wave heights under different EC characteristics, including cyclone translational speed and maximum winds, which have strong effects on wave height variability. Finally, a brief analysis of EC and wave climate under positive and negative phases of the North Atlantic Oscillation is presented.

Analysis Of Policy Has Been Established By The Minister On Opening The Export Of Lobster Seed In Indonesia

Seakeeping is the ship's ability to stay afloat on the waves. The ship's maneuverability is greatly influenced by external factors related to the state of the sea and the waters in which the ship sails. Calculating seakeeping with various variations of depth, current, and wave height is needed for ship safety when sailing in the calculation of seakeeping using linear strip theory to calculate the response of heaving and pitching movements while roll damping theory for rolling movements. In this study, the ship's motion is calculated using the Finite element method software Hydrodynamic Diffraction and Hydrodynamic Time Response. For variations in wave height and water depth, referring to the conditions of Indonesian waters, from the reference, variations in wave height of 3 m, and 5 m (based on sea state WMO). In contrast, the current variation uses a current with a speed of 10 knots and a current depth of 10 T, 15 T, and 20 T. Based on the data obtained in data processing, it can be seen that the high value of the wave frequency obtained at 90 and 270 degrees wave direction is relatively high. The value of the roll spectrum in the direction of 0 and 270 degrees is large and can cause rolling on the ship. In the direction of 0 and 270 degrees, the wave resistance can be reduced by th Lobsters are animals that enter into crustaceans that have problematic skin. Adult lobsters can generally be found on a stretch of sand with coral spots with a depth of between 5-100 meters. This condition will cause a low number of young lobsters in the waters. This research was conducted with a case study regarding the policy of opening lobster seed export, which aims to find out how the policy is to open the export of lobster seed. The data obtained is done by reviewing the literature on the internet. Based on the analysis, the export profit of lobster seeds has continued to increase every month since it was again allowed by the government in May 2020. Based on data from the Central Statistics Agency (BPS), lobster seeds began to be re-exported in June 2020 at 32 kilograms, costing the US $ 112,990. The government can help with training and outreach on lobster cultivation. The government can offer Lobster a partnership package to help people start a freshwater crayfish business.

Experimental Study on Mooring Tension of Porous-Slope Type Floating Breakwater

Floating breakwater is an alternative structure to fixed breakwater because of its effectiveness in coastal areas. Under certain conditions, floating breakwater is more flexible in design and more accessible in installation. The fundamental aspect of floating breakwater design is the mooring system to keep in position and determine the system's performance. This study uses physical modeling to determine the magnitude of maximum mooring stress on a mooring line. Moreover, several slope-porous floating breakwaters and pontoon types are examined. The floating breakwater model is constructed from polylactic acid, while the mooring line uses polyethylene. The physical experiment and testing are carried out in a wave flume with regular waves under several variations of wave height, wave period, slope angle, and porosity. It is cultivated that the mooring stress on the seaward position is always greater than on the leeward position since the seaward side will receive the first wave force, and the mooring line will dampen the wave force on the seaward side. However, the pontoon receives higher maximum mooring stress than the other models due to incoming wave forces that arrive on a vertical surface perpendicular to the direction of the waves. On the other hand, floating breakwaters with 5% porosity provide lower mooring stress than non-porous breakwaters. The greater the porosity is, the smaller the mooring forces are. The floating breakwater with 5% porosity can reduce the mooring stress by 16.5% (45 deg) and 13.5% (60 deg). At a slope of 45 deg, the maximum mooring stress received by the floating breakwater will increase by 8.5% and 5.3%, respectively, at 0% and 5% porosity.

Crack Analysis Due to Fatigue Load During Subsea Pipeline Installation

Most of the subsea pipelines in Indonesia are installed using the S-Lay method with the pipelay barges equipped with mooring spreads, tensioners, and stinger. During the subsea pipeline installation, static loads occur due to the pipeline configuration from the firing line of the pipelay barge up to the seabed. The pipe will experience axial tension and bending moment in two critical areas: overbend and sagbend. In addition, fatigue loads occur during subsea pipeline installation due to environmental loads (i.e., currents and waves). Defects that are found after welding will grow due to these fatigue loads. Crack analysis with a fracture mechanic approach known as Engineering Critical Assessment (ECA) is carried out by considering the fatigue load due to significant wave height variations for 0.5m, 1.0m, and 1.8m. BS 7910 is used as a standard reference to determine the allowable defects criteria for external and internal flaws. The depth of the defect (a) is simulated from a depth of 1mm – 3mm. The analysis found that the allowable defect length is decreased by 12.7% - 25.0% from a significant wave height of 0.5m to 1.8m for the external surface flaw. While for an internal surface flaw, the allowable defect length is decreased by 5.9% - 13.6% from a significant wave height of 0.5m to 1.8m. These results can be used as a basis for subsea pipeline installation contractors to perform fatigue load sensitivity and optimize the allowable defects based on the actual wave load at the site.