Abstract

In some lined channels with high gradients, a heavy scouring and erosion, as well as overflow, it is highly common to occur, thus it is required a water flow velocities regulation. An attractive option for reducing water flow velocities is to significantly increase their bottom roughness through the installation of rapid hydraulic structures which are one of the river trainings structures. This prevents the river bed against erosion, also stabilises the bed slope and helps to keep river channels stable under flooding conditions. However, in sedimentary density fluids, a consequence of the change of velocity is deposition of solids which could be consolidated with the result of changing the geometric design of the roughness element. This study aims to estimate the degree of confidence expected when modifications take place to artificial roughness geometries in the bottom of the channel with turbulent flow and density fluid. The modification corresponds from transverse ribs into ramps, so to establish the equations as result of this change, a mathematical analysis using the Buckingham's theorem was implemented. This theorem uses various dimensionless expressions as criterion for obtaining a high channel bottom roughness. The study allows us to conclude that the new generated bottom roughness causes more stable water flows and although it may be expensive, it is a recommended way to reduce flow velocities. In general, there is an interchange achieving a more stable operation, with a lower erosive capacity, in exchange for the channel having larger cross-sections.