Journal of Waterway, Port, Coastal, and Ocean Engineering

This paper presents the findings from an experimental investigation into the nature and extent of the scouring that occurs when a ship berths in front of a perpendicular quay wall within the confines of a harbor. It examines the interaction between the relative position of the quay wall to the central axis of the ship and the influence of the angle of the vessel’s rudder on the magnitude of the scouring produced. The experimental program covered a range of sediment sizes, propeller diameters and speeds of rotation, and rudder angles. Also, methods for calculating the depth of expected scour are presented in terms of initial semiempirical equations for the data range under investigation.

Different types of strengthening systems were introduced to protect the crest and land-side slope of the levees against surge overflow and wave overtopping after Hurricane Katrina. Three levee-strengthening systems, roller-compacted concrete, articulated concrete block, and high-performance turf reinforcement mat, were investigated through full-scale laboratory tests in this study. Hydraulic performances of these three levee-strengthening systems were compared to determine the effect of strengthening systems and to provide the equivalency analysis between surge-only overflow and combined wave and surge overtopping. The findings of this study indicate that the high-performance turf reinforcement mat system has the strongest effect in reducing and smoothing the overtopping discharge and in reducing the flow velocity and wavefront velocity on the land-side slope, whereas roller-compacted concrete has the weakest effect. Equivalency analysis between surge-only overflow and combined wave and surge overtopping reveals that the impact of waves on the overtopping discharge and flow velocity on the land-side slope during combined wave and surge overtopping is negligible when the relative freeboard $R_c/H_{m,0}<-0.3$. The equivalency relationships are proved to be applicable to all three tested strengthening systems and can be used to estimate the hydraulic overtopping parameters on levees under combined wave and surge overtopping conditions strengthened with roller-compacted concrete, articulated concrete block, high-performance turf reinforcement mat, or other strengthening systems.

The channel analysis and design evaluation tool (CADET) is a numerical program to determine the optimum dredge depth for the offshore portions of entrance channels. A brief description of the theoretical basis and risk assessment in CADET is presented. Validation comparisons between CADET predictions and field measurements of wave-induced vertical motions at Ambrose Channel, New York, are presented. Prototype ship motions were measured with a differential global positioning system in April 1998 along three 488-m-long reaches. Comparisons were made with six ships, three tankers and three containerships, during inbound and outbound transits. In general, the CADET predictions matched the field measurements reasonably well, especially considering the wave heights were relatively small during the measurement period.

In the probabilistic design of a breakwater armor layer, it is often necessary to calculate the damage accumulated over the breakwater's life cycle. In this paper, a comparison is made between existing methods to calculate the cumulative damage to the breakwater armor layer. In the current study, hydraulic experiments are conducted to gauge the damage progression of Tetrapod armor units. When severe damage occurs at the beginning of the breakwater's life cycle, the two methods do not differ significantly, but, in general, the latter predicts a larger cumulative damage than the former. For a Tetrapod armor layer, it is recommended that the average of the two methods be used.

Ship/boat wakes are identified in pressure and flow velocity records as chirp signals, which are also known as sweep signals in sonar and radar applications. A chirp is a signal in which the frequency increases or decreases with time. Wakes are analyzed using time-frequency techniques [windowed Fourier transform (WFT), wavelet transform (WT), and instantaneous frequency]. This approach allows for detecting boat wakes and studying their statistics, even in the presence of a relatively strong broad-banded wind-wave background. Time-frequency methods also open a new direction for the statistical description of wakes, which are applicable to the characterization of the wake climate (e.g., for sites with intense boat traffic). The usefulness of the time-frequency analysis on observations collected in 2010 at Jensen Beach, Florida will be demonstrated.

Placement of dredged spoils in a slurry form and allowing self-weight consolidation is common in land reclamation works carried out adjacent to water bodies. The influence of the settling behavior of soil particles in clay-water slurry on the homogeneity and consolidation properties of the final sediment were assessed in the current study. Standard one-dimensional and radial consolidation tests were conducted on Port of Brisbane dredged mud, which was remolded at various water contents and salt concentrations and reconstituted. Particle-size distribution curves show the various degrees of segregation that occurred during settlement of soil particles in flocculated and dispersed slurry, prepared and placed in saltwater and freshwater environments, respectively. The vertical and horizontal consolidation coefficients ($c_v$, $c_h$) and the vertical permeability ($k_v$) were found to be fairly uniform throughout the flocculated sediment, whereas for the dispersed sediment significant variation could be observed at various depth levels. The consolidation properties in the horizontal direction ($c_h$, $k_h$) were considerably larger than in the vertical direction ($c_v$, $k_v$) for both the flocculated and dispersed sediment. The degree of anisotropy in the consolidation coefficient, measured by $c_h\text{/}{c}_v$, was generally larger for the flocculated sediment than for the dispersed sediment. Proper understanding of the consolidation process and the variability of the consolidation and permeability coefficients with depth is important for the reliable prediction of settlement and the degree of consolidation achieved in the reclamation fill.

Measurements of the characteristics of a solitary wave propagating alone or against a current were performed using superresolution particle image velocimetry (PIV). The velocity field was obtained when the solitary wave passed in front of a high-speed charged-coupled device camera. The instantaneous and spatial surface profiles were measured using four resistance wave gauges and the particle mask correlation method that was applied to monitor tracers seeded into the flow field. In addition, an algorithm was employed to track water particle paths in a two-dimensional scheme. The trajectory measured using the superresolution PIV was compared with the one modeled using the solitary wave theory. This flow visualization technique was applied to analyze the collision of two solitary waves propagating in the same and in opposite directions.

An observational wave study was conducted to test empirical relations and compare with numerical model results in shallow water environments. Relations among nondimensional water-depth, nondimensional wave-energy, and nondimensional peak-frequency are presented based on both subsurface pressure and velocity time-series collected in Galveston Bay, Texas. The values reported here provide further confirmation of nondimensional wave parameterizations over a range spanning two orders of magnitude of the nondimensional depth. A comparison of observed wave statistics (significant wave heights, peak periods, and wave directions) to numerical model hindcasts was found to be in good agreement with the observations. Further inspection of the observed and modeled energy spectra showed that peak periods were in good agreement, although the modeled spectra were less peaked.

The Lower Mississippi River protrudes into the Gulf of Mexico, and manmade levees line only the west bank for 55 km of the Lower Plaquemines section. Historically, sustained easterly winds from hurricanes have directed surge across Breton Sound, into the Mississippi River and against its west bank levee, allowing for surge to build and then propagate efficiently upriver and thus increase water levels past New Orleans. This case study applies a new and extensively validated basin- to channel-scale, high-resolution, unstructured-mesh ADvanced CIRCulation model to simulate a suite of historical and hypothetical storms under low to high river discharges. The results show that during hurricanes, (1) total water levels in the lower river south of Pointe à La Hache are only weakly dependent on river flow, and easterly wind-driven storm surge is generated on top of existing ambient strongly flow-dependent river stages, so the surge that propagates upriver reduces with increasing river flow; (2) natural levees and adjacent wetlands on the east and west banks in the Lower Plaquemines capture storm surge in the river, although not as effectively as the manmade levees on the west bank; and (3) the lowering of manmade levees along this Lower Plaquemines river section to their natural state, to allow storm surge to partially pass across the Mississippi River, will decrease storm surge upriver by 1 to 2 m between Pointe à La Hache and New Orleans, independent of river flow.

The risk-based design of a reef breakwater requires the prediction of the temporal variations of the damage and wave transmission coefficient during storms. The cross-shore numerical model is extended to the landward zone of the wave transmission. The extended model is compared with 148 tests for a reef breakwater with a narrow crest at or above the still water level where the narrow crest was lowered by wave action. The model is also compared with an experiment on a wide-crested submerged breakwater in which the crest height increased during 20-h wave action. The damage, crest height, and wave transmission coefficient are predicted reasonably well; however, the damaged profile is not predicted accurately.