Journal of Waterway, Port, Coastal, and Ocean Engineering

The evaluation, selection, sequencing, and scheduling of lock reconstruction and rehabilitation projects is a major concern for inland waterway systems. As traffic increases and existing lock conditions deteriorate, users suffer substantially longer processing times and delays. Lock projects tend to be interdependent as improvements at one lock may shift bottlenecks elsewhere. A generalized waterway simulation model that is independent of network geometry was developed to evaluate the system over a multiyear planning horizon. A genetic algorithm was also developed in order to efficiently explore the solution space of this large investment optimization problem. The proposed combination of two stochastic models can solve selection, sequencing, and scheduling problems for interdependent projects in large waterway networks but requires long computation times. Due to lock interdependency, the benefits of multiple projects are not directly obtainable by adding individual project benefits; they are measured from the marginal increment of total system delays. The results show how interdependent projects should be scheduled and how operational lock control improvements can sometimes improve delays significantly without requiring major construction investments.

A study of flow behavior, namely, pollutant dispersion and trapping near a headland recirculation zone adjacent to it was undertaken experimentally in the Manchester Tidal Facility for steady flows. The planar laser-induced fluorescent technique was used to visualize the flow patterns both horizontally and vertically. Dye was released using a preburied dye diffuser in the bed to simulate trapped pollutant released from the rough bed, and also through a tube placed at middepth to simulate the case of ocean outfall discharges. The discharge points chosen were within the recirculation zone, between the recirculation zone and the main current, and at a point near the main current where the flow changes. For middepth discharges the dye tended to stay near the surface, whereas for dye diffuser discharges the dye stayed near the boundary layer, and also exhibited a three-dimensional plume structure. Trapping was significant especially for certain discharge points in the recirculation zone due to the slower velocities.

This paper presents the results of an experimental study of the scour created by a siphon flow through a vertical tube of diameter $d$ of 9.7 to $20.4\mathrm{mm}$ in a cohesionless sand bed of approximately uniform size $D$ of $0.58\mathrm{mm}$ . The position of the inlet of the siphon tube ranged from $-101.6$ to $6.4\mathrm{mm}$ relative to the surface of the sand bed and the velocity of flow through the tube $U_0$ varied from 0.34 to $6.41\mathrm{m}∕\mathrm{s}$ . Data from this and previous studies are used to show the radial extent of the scour hole and the maximum depth of scour depend primarily on the densimetric Froude number ${\mathsf{F}}_0$ , where ${\mathsf{F}}_0=U_0∕\sqrt{g\left(\Delta \rho ∕\rho \right)D}$ , $g$ is the gravitational acceleration, $\Delta \rho$ is the difference in density between the sediment and fluid, and $\rho$ is the density of the fluid. A theoretical analysis of the problem is used to further assess the data and it is found that viscous effects are also important to consider. The profile of the scour hole at equilibrium, for all tube positions, is found to be similar when the scour depth is measured relative to the tube inlet.

This work compares the spectral analysis of ocean wave fields performed from nautical radar and waverider buoy measurements. The data were taken by a radar station located in the northern coast of Spain and by a buoy that was moored close to the area covered by the radar for its calibration. In this area the sea states are mainly dominated by the presence of northwest swells coming from storms originating in the North Atlantic Ocean. In this order, the radar calibration and the comparisons of different spectral parameters and scalar spectra from both sensors are presented.

The use of submerged vanes to divert sediment movements on seabed and open channel flows are common in many engineering projects. In the present study, experiments were conducted to investigate the characteristics of flow and sediment motion around a submerged vane in a large flume, $30\mathrm{m}$ long, $6\mathrm{m}$ wide, and $0.6\mathrm{m}$ high, paved with lightweight cylindrical plastic material with specific gravity of 1.05. The size of the uniform plastic material is $2.8\mathrm{mm}$ in diameter and $3.1\mathrm{mm}$ in height. The vane was made of $10\mathrm{mm}$ thick steel plate. The height of the vane above the mean bed ranged from one-eighth to one-third of the flow depth and its length is between $1\text{to}4\mathrm{m}$ . The alignment of the vane to the approach flow varied from 15° to 90°. The effectiveness of the submerged vane in sediment diversion depends on the vane alignment to the approach flow, and the height and length of the vane. The optimum skew angle to the approach flow for the purpose of sediment diversion is about 30°. The optimum vane height of two to three times the height of the bedform would be able to resist the bedload “escaping” over the bedform crest.