Critical revision of check dams hydraulic design criteria

This paper addresses the problem of sizing the spillway of a closed check dam. Check dams are structures designed to control the solid transport and morphology of mountain streams. Paradoxically, however, their spillways are typically sized in clear-water conditions. The paper first analyses the behaviour of a check dam under clear water and then under live-bed conditions which is by far the most frequent operating condition. The theoretical approach is based on the conservation equations of solid mass, total mass, momentum and energy of the flow. The results of the theory are then compared with the results of some experiments in a laboratory channel equipped with a closed circuit for solid and liquid flow rates. The comparison between experiments and theory shows the validity of the approach. As expected, in some conditions that are far from rare, the design made in the clear-water condition is not safe.