An important feature of most rivers and canals is their habitats for a rich of aquatic vegetation which is extremely important from an environmental and ecological point of view. These variations in habitat mean that it is rare to find a cross-section of a natural channel which has the same roughness along its perimeter. In these channels, flow conditions lead to a complex flow situation with i...

[1] Results are presented from a field investigation of near-bed turbulence above degrading waveformed sand ripples in 17-m water depth on the inner shelf. The heights of the 50-cm wavelength primary ripples were about 5 cm at the start of the observation period, and decreased by a factor of 2 within 15 days. The principal degradation mechanism involved fish making pits in the seafloor. Near-be...

A natural reach of montane stream (length 96 m and 7 m width) was grided into 150 cells (2 × 2 m). Density and biomass of fish (Salmo trutta L. and Cottus poecilopus Heckel) were estimated at each cell, as well as stream depth, current velocity, Froude number, bed granulation and its roughness were measured, and benthic samples from exposed bricks were collected from mid August to early October...

Large-eddy simulations (LES) of the flow over a non-uniformly roughened channel bed are carried out to study the effect of non-uniform bed roughness on turbulence driven secondary currents and turbulence statistics. The channel bed is comprised of alternating rough and smooth strips, the width of which corresponds to the water depth. The Reynolds number based on hydraulic radius and bulk veloci...

A tidal bore is a wave propagating upstream as the tidal flow turns to rising. It forms during spring tide conditions when the flood tide is confined to a narrow funneled channel. To date, theoretical and numerical studies rely upon physical experiments to validate the developments, but the experimental data are limited mostly to visual observations and sometimes free-surface measurements. Here...