Non-prismatic channels for reducing shear stress

To reduce the sediment transport capacity, shear stress needs to be reduced as well. The article describes work that has been done to find a way to make these reductions possible. The theoretical study and the approach proposed allowed us to obtain a general equation that determines conditions and calculates the most important parameters which support the reduction of shear stress. This describes the mechanism that erodes soils by free surface water flow. In a similar vein, we have shown that adding a short non-prismatic channel to the entrance of a prismatic channel, which has the same geometric shape, is a very powerful way to reduce shear stress. With the idea of reducing shear stress, we have shown that the water-surface profile type plays a key role and must therefore be included in future reflections on reducing the importance of shear stress. Additionally, the notion of efficiency was introduced that allows to evaluate the expected gain after the reduction of shear stress and adding a short non-prismatic channel. The laws of similarity applied to free surface flows allowed us to obtain an equation with several equivalence scales and compare different geometric shapes in terms of their efficiency in the reduction of shear stress.