Abstract
To maintain inland navigation, a deposition crest in the Hunlock area, in the Upper Meuse River, Belgium, has to be dredged almost every two years. A long-term solution is searched for, based on the understanding of water velocity field and solid transport processes, to avoid the silting and the expensive dredging. The physical process is analysed thanks to a 1:50 small-scale model of the 500 m-long Meuse reach with Hun movable dam as upstream boundary. The velocity fields, recorded with an electromagnetic probe displaced automatically, are compared for several configurations. Three discharges and distinct dam openings are tested in the existing configuration. Modifications of the downstream guard wall, by perforating ports, are also considered. Building groynes in the right side of the river is analysed. Finally, flushing water through the lock is tested. As conclusions, alluviations are due to the localisation of the lock in an enlarged area of the Upper Meuse and in a meander intrados, inducing decreasing flow velocities. None of the tested solutions is completely convincing according to 4 criterions: (1) ability to decrease the deposition crest, (2) navigation requirements, (3) safety in case of high-stage discharges, and (4) acceptable cost.
Highlights
To ensure a safe and efficient inland navigation, the water depth has to be sufficient in the waterways
The small velocities are due to 2 phenomena: (1) the lock is located in a significant enlarged area of the Upper Meuse in comparison with the mean width and (2) the lock channel is built in a meander intrados
The flow crossing the dam is mainly directed towards the meander extrados, i.e. the right side of the Upper Meuse, while the downstream lock channel in the left side is hidden by the river inflexion point and by the guard wall
Summary
To ensure a safe and efficient inland navigation, the water depth has to be sufficient in the waterways. This paper is devoted to the deposition crest in the Hun-lock area, which has to be dredged almost every two years. A long-term solution is searched for, based on the understanding of water velocity field and solid transport processes, to avoid the expensive dredging. A movable hydropower station is installed in the right sluice (P1) It is designed in the following way: at low discharge, the gate is opened in such a way that the main discharge flows through the turbine; when the discharge increases (above 500 m3/s), the hydropower unit is lifted out of the flow to let the gate recover the control (up to 1800 m3/s). The bathymetry collected in the field in 2015 (Fig. 1) shows the deposition crest forming at the lower lock approach (red and yellow area) with a maximum level zb,max,p = 82.6 m above the sea level.
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