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The ship-generated waves in restricted waterways can influence the behavior of sediment resuspension and bank erosion. This paper explores the case study considering the effect of ship-generated waves in restricted channels. A fully nonlinear Boussinesq model (FUNWAVE-TVD) is used to simulate the ship-generated waves. The sediment transport model adopted in FUNWAVE has been changed to incorporate the modified diffusion coefficients, deposition flux, and an explicit equation for settling velocity and critical shield parameter. The sediment transport model was validated against the experimental results of solitary waves in a wave tank, and model performance in shoreline geometry was reported. The implementation of the moving vessel in the numerical model and its impact on suspended sediment concentration were evaluated against the field measurements in the Falta stretch of the Hooghly river in Indian National Waterway 1. The error value in predicting the depth-averaged suspended sediment concentration by the FUNWAVE module was 97.6%, which has been significantly reduced to 16.3% based on the present modification. The parametric study of the ship waves in a typical restricted waterway of India revealed that the concentration of the sediments gradually decreases from the navigation channel to the river banks due to dissipation in the ship waves. The change in wave height and depth-averaged sediment concentration increases with the increasing depth Froude number. Finally, the impact on sediment transport due to different scenarios, such as the movement of two vessels in close proximity, the passage of vehicles coming from the opposite direction on the navigation channel, the influence of small draft vessels, and the bed morphology changes due to the multiple vessel movements are analyzed and reported. [ABSTRACT FROM AUTHOR]

The ship-generated waves in restricted waterways can influence the behavior of sediment resuspension and bank erosion. This paper explores the case study considering the effect of ship-generated waves in restricted channels. A fully nonlinear Boussinesq model (FUNWAVE-TVD) is used to simulate the ship-generated waves. The sediment transport model adopted in FUNWAVE has been changed to incorporate the modified diffusion coefficients, deposition flux, and an explicit equation for settling velocity and critical shield parameter. The sediment transport model was validated against the experimental results of solitary waves in a wave tank, and model performance in shoreline geometry was reported. The implementation of the moving vessel in the numerical model and its impact on suspended sediment concentration were evaluated against the field measurements in the Falta stretch of the Hooghly river in Indian National Waterway 1. The error value in predicting the depth-averaged suspended sediment concentration by the FUNWAVE module was 97.6%, which has been significantly reduced to 16.3% based on the present modification. The parametric study of the ship waves in a typical restricted waterway of India revealed that the concentration of the sediments gradually decreases from the navigation channel to the river banks due to dissipation in the ship waves. The change in wave height and depth-averaged sediment concentration increases with the increasing depth Froude number. Finally, the impact on sediment transport due to different scenarios, such as the movement of two vessels in close proximity, the passage of vehicles coming from the opposite direction on the navigation channel, the influence of small draft vessels, and the bed morphology changes due to the multiple vessel movements are analyzed and reported. [ABSTRACT FROM AUTHOR]

The mechanisms of fluid mud formation and its characteristics are far from clear in the deep-dredged waterway in Xiamen estuarine bay. Some experiments were conducted in the muddy estuarine bay of Xiamen when Super Typhoon Meranti, which was the strongest typhoon to have affected the area over the last 70 years, struck and after it passed. Contrary to expectation, results reveal that typhoon-induced waves are not the main hydrodynamic forcing that transport sediment. The influence of fluvial flooding and ebb tidal flow results in high concentrations (greater than 14 kg/m3) of suspended sediment in a layer near the bed, which may either deposit or be released directly into the waterway to form fluid mud. Further, new indicators are proposed, namely, river discharge and fluvial flood duration, to describe quantitatively the conditions under which fluid mud forms; it is in fact likely to form in the waterway when a discharge greater than 1,000 m3/s lasts for more than one day. The new indicators may be applied as reference by waterway administrators in their operations. [ABSTRACT FROM AUTHOR]

This work aims to shed some light on longshore sediment transport (LST) in the highly energetic northwest coast of Portugal. Data achieved through a sand-tracer experiment are compared with data obtained from the original and the new re-evaluated longshore sediment transport formulas (US ACE Waterways Experiment Station's Coastal Engineering and Research Center, Kamphuis, and Bayram bulk formulas) to assess their performance. The field experiment with dyed sand was held at Ofir Beach during one tidal cycle under medium wave-energy conditions. Local hydrodynamic conditions and beach topography were recorded. The tracer was driven southward in response to the local swell and wind- and wave-induced currents (Hsb = 0.75 m, Tp = 11:5 s, θb = 8 - 12°). The LST was estimated by using a linear sediment trans-port flux approach. The obtained value (2.3 x 10-3 m³ ⋅ s-1) approached the estimation provided by the original Bayram formula (2.5 x 10-3 m³ ⋅ s-1). The other formulas overestimated the transport, but the estimations resulting from the new re-evaluated formulas also yield approximate results. Therefore, the results of this work indicated that the Bayram formula may give satisfactory results for predicting the longshore sediment transport on Ofir Beach. [ABSTRACT FROM AUTHOR]

This paper presents findings from an extensive, laboratory-based study of scour at bridge abutments located in compound channels. The study considered aspects of abutment construction, including abutment and floodplain erodibility, and examined how these aspects influence scour development. Its findings show that three basic scour conditions can develop at abutments in compound channels: scour of the main-channel bed, when the floodplain is far less erodible than the bed of the main channel (Scour Condition A); scour of the floodplain around an abutment, for abutments set back on a floodplain (Scour Condition B); and scour at an abutment column exposed once an abutment is breached (Scour Condition C). These conditions may combine, depending on abutment location and site circumstances. The authors present laboratory observations and data associated with Scour Conditions A and B. The data are analyzed in terms of a formulation concept that treats Scour Conditions A and B as essentially scour at a short contraction (the bridge opening), for which flow nonuniformity and turbulence amplify scour depth associated with a long contraction. The amplification is greatest for small contractions and diminishes for larger contractions that force greater magnitude and uniformity of flow velocity through a bridge opening. [ABSTRACT FROM AUTHOR]

This paper presents a two-dimensional morphological model for unsteady flow and both suspended-load and bed-load transport of multiple grain size to simulate transport of graded sediments downstream from the Three Gorges Reservoir. The model system includes a hydrodynamic module and a sediment module. The hydrodynamic module is based on the depth-averaged shallow water equations in orthogonal curvilinear coordinates. The sediment module describing nonuniform sediment transport is developed to include nonequilibrium transport processes, bed deformation, and bed material sorting. The model was calibrated using field observations through application to a 63-km-long alluvial river channel on the middle Yangtze River in China. A total of 16 size groups and a loose layer method of three sublayers were considered for the transport of the nonuniform bed materials in a long-term simulation. Predictions are compared with preliminary results of field observations and factors affecting the reliability of the simulated results are discussed. The results may be helpful to the development of more accurate simulation models in the future. [ABSTRACT FROM AUTHOR]

During the summer of 2005, a tidal creek (“Pine Gully”) within a few kilometers of the Houston Ship Channel was completely blocked by a 200 m long and 1.5 m deep plug of silt and fine sand. This paper documents and explains this unusual sedimentation event. It then presents a new method for calculating ship wave-induced sediment transport into tidal creeks. Between November 2005 and January 2006, measurements of velocity, pressure, and suspended sediment concentration were taken in the creek approximately 150 m seaward of the plug. The data indicated ship wave-induced bores (one per ship). Each bore caused a net sediment transport of approximately 0.4 m3 toward the plug, enough to explain the observed rate of sediment accumulation. Cores of the plug showed that the plug material was consistent throughout, suggesting a single pathway (from the bay). During the period of plug formation, rainfall and creek discharge were relatively low indicating a likely factor for the plugging. Model calculations showed that significant ship wave-induced sediment transport into Pine Gully would occur only when Pine Gully mean depth is less than 0.8 m. [ABSTRACT FROM AUTHOR]

A negative bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) is attributed to the movement of sediment on or near the streambed, and is an issue widely acknowledged by the scientific community. The integration of a differentially corrected global positioning system (DGPS) to track the movement of the ADCP can be used to avoid the systematic bias associated with a moving bed. DGPS, however, cannot provide consistently accurate positions because of multipath errors and satellite signal reception problems on waterways with dense tree canopy along the banks, in deep valleys or canyons, and near bridges. An alternative method of correcting for the moving-bed bias, based on the closure error resulting from a two-way crossing of the river, is presented. The uncertainty in the mean moving-bed velocity measured by the loop method is shown to be approximately 0.6 cm/s. For the 13 field measurements presented, the loop method resulted in corrected discharges that were within 5% of discharges measured utilizing DGPS to compensate for moving-bed conditions. [ABSTRACT FROM AUTHOR]