Journal of Waterway, Port, Coastal, and Ocean Engineering

Geotechnical surface sediment properties and behavior contribute to the success of wetland conservation and remediation actions, but the correlation between geotechnical sediment characteristics and active morphodynamics in such areas is still poorly understood. Therefore, a field investigation of surficial sediments was conducted in wetland waterways in the Terrebonne Parish, the St. Bernard Parish, and the Rigolets in coastal Louisiana. In situ tests were conducted at 290 locations using a portable free-fall penetrometer, supported by seven sediment core samples and data available from the literature. The results allowed the authors to map changes in sediment strength and stratification and discuss them with regard to local site characteristics, such as sediment type, abundance of vegetation, and vicinity to human-made structures and engineering activities, and to the local geomorphology. Stiff sediments were observed at submerged banks and bars. Two lakes differed significantly in their sediment-strength profiles, indicating differences in sediment-deposition history. Meandering resulted in an asymmetry of the geotechnical cross-channel profile. In summary, geotechnical sediment characteristics seem to reflect the inferred local sediment dynamics.

A typhoon is one of the major factors that often cause sediment transport and bed erosion in estuarine navigational channels. A 12.5-m deepwater navigational channel (DNC) is located in the north passage of the Changjiang Estuary. Because it acts as the entrance navigation waterway of the Changjiang River, it is important to investigate the impact of typhoons on sediment suspension and transport in the navigation channel. In this study, a previously calibrated hydrodynamic and sediment transport model [shallow-water equation model (SWEM)] was integrated with a storm wind model [weather research and forecasting (WRF)] and a wave model [simulating waves nearshore (SWAN)] to investigate the effect of Typhoon Damrey on the navigation channel in 2012. The typhoon produced a weak storm surge but significant wave heights in the Changjiang Estuary. By comparing bottom shear stress induced by current and wave, numerical modeling results indicated that the increase of sediment concentration in the navigation channel during Typhoon Damrey was mainly caused by sediment transport fluxed into the channel from shallow-water areas outside the channel, where wave-induced bottom shear stress during Typhoon Damrey caused sediment resuspension. The high sediment flux overtopping from the south dike into the channel was the important sediment source for the navigation channel. During the passage of Typhoon Damrey, there was a convergence area of sediment flux between the upstream seaward sediment transport and the lateral transport of sediment flux overtopping from the south dike at the middle-lower reach of the north passage. Near the outlet of the north passage, the near-bottom residual transport of sediment was in the upstream direction against the seaward sediment transport from the river. The convergences of sediment flux produced the high-turbidity maximum zone at the lower reach of the north passage, where in situ bathymetric surveys within the DNC before and after Typhoon Damrey showed the sediment deposition area in the channel.

Periodic beach-fill placement and frequent overwash result in net offshore and onshore sand transport, respectively. Three tests consisting of fifty 400-s runs were conducted in a small-scale wave flume to examine the effect of net cross-shore sand transport on an equilibrium profile. The foreshore of an equilibrium profile with no net sand transport shifted seaward after periodic sand placement near the shoreline. Frequent sand overwash resulted in the landward shift of the shoreline. The profile changes for the three tests were relatively small and the shoreline shifts were less than 0.1 m. An analytical model for an equilibrium profile with net cross-shore sand transport was developed by approximating existing formulas for onshore bed load and offshore suspended sand transport in the inner surf zone. The model predicted the horizontal shift of the equilibrium profile under net cross-shore sand transport, which was the maximum at the shoreline and approached zero at the closure depth. The model calibrated using the three tests was used to estimate the seaward shift of the shoreline on periodically nourished beaches on a prototype scale.

A ship is generally characterized by three principal elements: the propulsive system, the steering system, and the hull geometry. The interaction between these elements is very strong; therefore, it is essential to be able to estimate the effect of this interaction for better control and prediction of the ship’s trajectory. This interaction is mostly affected by the drift angle, rudder angle, propeller rotation rate, and form of the stern hull. However, for ships navigating on inland waterways, the ratio, h/T, of the water depth, h, to the ship’s draught, T, can significantly affect this interaction. In this paper, we present the results of a full numerical study about the impact of the navigation environment (deep and shallow waters) on the hull–propeller–rudder interaction. A scaled inland container ship with twin propellers and quadruple rudders was selected to carry out this work. A steady computational fluid dynamics (CFD) code based on Reynolds-averaged Navier–Stokes (RANS) equations was validated and used to simulate the flow around the hull, propellers, and rudders. The flow was considered with a free surface and full turbulence. The influence of the confined environment on the force interaction was investigated by simulating various operating configurations of a ship; therefore, several values of the ship’s underkeel clearance, rudder angles, and propeller thrust loading were tested. The results of this work clearly show the influence of each parameter tested and confirm that the hull–propeller–rudder interaction is strongly impacted by waterway confinement.

This paper proposes an experimental study of the hydro- and morpho-dynamics induced by a slender vertical pile fitted into a sandy seabed and forced by sea waves in finite waters. The scour depth at the pile and the seabed morphology around it were measured and analyzed for both regular and random wave forcing. Scour depths due to regular waves were compared to those predicted in a previous study, revealing good agreement. The maximum scour depth occurred at the lateral side of the pile for waves characterized by a Keulegan-Carpenter (KC) number smaller than 7–8 and behind the pile for waves with KC > 7–8. Such a result revealed an asymmetric effect on the scour depth because of the weaker reversal flow. This behavior was more evident for nonlinear waves being crests larger than troughs and, as a consequence, vortices, responsible for the scour processes, became even more energetic around crest stages. To better understand the dynamics in front of, around, and behind the cylinder, pressure measurements were obtained to evaluate the generation and evolution of vortices. The pressure data showed that the adverse pressure gradient around the pile was higher than on the upstream of the pile. The analyses of the pressure data seemed to confirm that, if the forcing was only due to waves, the effect of the lee-wake vortices on the scour depth around the cylinder was stronger than that due to the horseshoe vortices. Finally, the practical stochastic method proposed by previous authors to compute the maximum scour depth around a vertical pile exposed to random waves was verified. The best adaptation between measured and predicted scour depths was obtained by taking into account approximately half of the highest waves (instead of one-tenth) over the threshold; such a condition is still cautionary for a practical point of view. A simplification of the previously discussed methodology was proposed in which the characteristic wave that generates the scour depth is defined.

In the offshore field, helical piles are being considered as a novel offshore pile system because of their flexibility regarding ease of installation and the large uplift capacity they can generate. This paper analyzes 120 cases in sand for different friction angle values, from 30 to 45°, considering five uplift forces, i.e., 5 to 25 MN, and three different wing ratio values (i.e., helix-to-shaft ratio). By using two different uplift capacity equations, the resulting embedment depths, depending on soil conditions and uplift axial force, are obtained. Torque was assessed with a model considering the relationship with the uplift capacity for deep helical piles in sand. Installation power was also initially assessed taking into account the torque and the crowd force. Calculations show that torque increases with the increasing helix diameter for the same geotechnical properties of the sand. Also, during installation, induced shear stress in the pile may be too high if the standard yield strength of steel is assumed.

Intake canals are used to withdraw water from rivers for various purposes. Sedimentation in the intake canal reduces the quality and quantity of water being delivered. In this study, experiments were conducted to control sediment entry into an intake channel using submerged vanes in a physical model with a rectangular mobile-bed main channel and a trapezoidal rigid-bed intake channel diverting at an angle of 45°. The variables in the study included vane angle, number of vane rows, and vane spacing in terms of mean flow depth in the main channel. In addition to the commonly used vane array with uniform vane heights, three other vane-height configurations were also tested. The least local scour around vanes and highest sediment reduction (∼70%) were observed for vanes oriented at a 15° vane angle with an increasing vane-height configuration placed in two rows. It was also observed that control of sediment entry into the intake canal increased with an increase of both vane spacing and number of vane rows.

The many locks built in the development of inland waterborne transport networks in past decades have become major bottlenecks in the China waterway system. Capacity has become one of the most important waterway lock characteristics. However, capacity is difficult to determine because it varies with the operating conditions. Although a traffic simulation is suitable for analyzing lock capacity, a reasonable analytical model may be more feasible and efficient, especially in the planning stage. The typical analytical model loses adaptability when the sizes of navigation locks and freight vessels are not uniform. Moreover, the lock capacity should have enough reserve to meet the peak demand under heavy traffic flow to provide the required level of service. In this article, an improved analytical model for estimating the lock capacity based on the load factor of the chamber area, relationship between the area and tonnage (RAT) of a freight vessel, and daily peak factor with a certain guarantee rate is presented. Three interrelated indicators (i.e., guarantee rate, traffic load, and time delay) are used to measure the lock level of service (LLOS) comprehensively. LLOS criteria and threshold values are proposed for the current conditions in China. Based on field data regarding the Beijing-Hangzhou Grand Canal, Yangtze River, and Xijiang River, the validations show that the improved model is reasonable, feasible, and very useful for an inland waterway network with nonuniform lock and vessel sizes. Additionally, optimal scheduling can be conducted based on the improved model to promote the development of uniform freight vessels in fully loaded operations as much as possible.

A new definition of wave groupiness factor is proposed here based on wave-height history of wave trains. This new definition takes into account the dual roles of both zero-downcrossing wave height and wave period in the spatial and temporal evolution of the wave groupiness. It is demonstrated that the new groupiness factor is less sensitive to the operational definition and can describe the groupiness degree of not only linear wave trains but also highly nonlinear ones. The variation of the wave groupiness across a laboratory fringing reef was investigated. Results showed that in the nonlinear shoaling zone, the groupiness became more pronounced. Decreasing of the groupiness was triggered by wave breaking in the vicinity of the breakpoint. The groupiness decreased rapidly shortly after breaking, whereas it increased in the inner surf zone. Infragravity wave modulation of short-wave water depth was the main source of groupiness after breaking.

In this article, we demonstrate that the normalized runup heights, R/H₀ (R = runup height; H₀ = incident wave height), for breaking solitary and periodic waves can be characterized by a single dimensionless parameter, called the surf parameter, which is defined by a theoretical wave-breaking criterion. Existing laboratory data for both breaking solitary and periodic waves were collected and are summarized in this article. Breaking waves include surging, plunging, and spilling breakers. To enhance the range of surf parameters for breaking solitary waves, a set of new laboratory experiments was carried out in a large-scale wave flume with a 1/100 slope. The maximum runup heights and the corresponding breaker types were recorded. Several wave conditions in the experiments were on the borderline of plunging and spilling breakers. When the laboratory data were plotted against the surf parameter, they collapsed into a trend, which can be described by a best-fit curve. This empirical formula can be used to provide a quick estimation of maximum runup height for both breaking solitary and periodic waves in the laboratory scale.

A Bayesian inverse framework is developed to optimize the skill of a predictive numerical model via interpolation of bathymetric measurements to provide the most probable bathymetric surface. The numerical model is a coupled wave flow model and predicts wave and hydrodynamic information (e.g., significant wave height and longshore velocity). The Bayesian method, coupled with Markov chain Monte Carlo (MCMC) optimization, is used to find the bathymetric field, which serves to minimize the residual errors between measured data and the corresponding numerical model results. By using a Bayesian approach, the range of probable model parameters is inferred from the observed data. Monte Carlo simulation is also applied to this numerical model to perform the uncertainty analysis of the model output fields (wave height and flow velocity). This analysis is performed by taking random samples from the probability distribution function (PDF) of inputs and running the model as required until the desired precision (±0.05 m for significant wave height) in output fields is achieved. The case study used in this analysis is the DUCK94 experiment, which was conducted at the US Army Field Research Facility at Duck, North Carolina, in the fall of 1994. The unknown model parameters for the hydrodynamic model involve those controlling bathymetric resolution. Furthermore, the ability of the statistical model to estimate the observed data is tested by running the forward model for two sets of input parameters: the estimated input parameters updated by the previously mentioned statistical model and the prior (noninformative) parameters. Using the model parameters estimated from the Bayesian analysis leads to improved comparisons to data. Using the presented method, the relative errors between the model outputs and the observed data for significant wave height at nearshore gauges is reduced by 30%.

In this article, validation of numerical models of ship wave-induced motions in port-approach channels is carried out. A selected set of high-quality data from recent full-scale trials measuring vertical motions of container ship transits entering and leaving the Port of Fremantle, Western Australia, is used. The measured wave-induced heave, roll, and pitch motions of six example container ship transits are discussed in detail, together with descriptions of in situ wave measurements and wave spectral analysis. A linear strip method, as implemented in the computer code OCTOPUS, is applied to predict the ship wave-induced motions. A comparison is made between measured and predicted ship motion responses to validate the ship motion software, and the measured roll response can be particularly used to assess the suitability of existing roll damping methods at full scale. The method is shown to give predictions of heave, roll, and pitch responses with reasonable accuracy for container ships at full scale in open dredged channels. Large-amplitude long-period roll motions were observed in some cases of the present trials, and unexpected harmonic pitch motions were also observed in other cases. Further research is recommended to study these seemingly nonlinear effects.

The study uses a 35-year data set, which can be used to provide a long-term assessment for assessing wave power resources, availability for wave energy converters (WECs), and multithreshold accessibility suitable for numerous vessels and important for offshore maintenance operations. The data set demonstrates that winter months have harsher environmental conditions for the Western regions, such as the Spanish coastlines, and the Eastern regions, such as the Aegean Sea, record slightly higher waves during summer months. The data set also identifies the seasons with lower resources, which will have higher accessibility and will benefit offshore construction and maintenance operations for offshore energy activities. It has been shown that the availability for wave energy depends on the operational range of a particular type of WEC; hence, threshold selection affects the availability distribution more than accessibility. Availability varies per region, with Southern Aegean, Southern Italian, and North African coasts having higher monthly values. Accessibility in nearshore areas is constantly over 90%, with deeper waters presenting reduced levels. Statistical analysis performed for this work shows predictable availability due to lower maxima, potentially enhancing WECs operation; this, however, will depend on device properties. Furthermore, the resource analysis indicates that the dominant metocean conditions yield low wave height range.

A work condition monitoring system is widely used for recording the real-time states of cutter suction dredgers during the dredging process. However, the obtained data cannot provide enough actionable information directly for construction efficiency. This paper presents a novel method to evaluate the construction efficiency of cutter suction dredgers from the perspective of construction cycles. The construction cycle related to dredging operations was first introduced. A new algorithm of selecting cycle characteristic parameters (ASCCP) was proposed to determine the cycle characteristic parameters. Combined with three-dimensional (3D) visualization of the dredging track of the dredger, the method of construction cycle recognition was established. Then, the efficiency-evaluation methods based on construction cycles and the time-utilization ratio were adopted to evaluate the construction efficiency. Finally, a case study showed that the proposed approach was feasible to evaluate the construction efficiency of the cutter suction dredger. Moreover, the methods of the present work can be implemented in any cutter suction dredger and aid construction project managers in managing equipment-related work tasks on construction sites.