Roughened Channels with Cross Beams Flow Features

The implementation of roughened channels with cross beams (RCCB) in drainage systems reduces the negative effects of high kinetic energy on flood flows, such as the increased erosion of infrastructures or of the ground. This paper aims to highlight the importance of using RCCB in drainage systems and to contribute to a better knowledge of flow characteristics in RCCB. The performance of RCCB was studied under diverse conditions through the use of a physical model in which several cross beams were installed with different thickness, longitudinal spacing between them, and at different heights. Results of free-surface profile, pressure head, and velocity measurements for different arrangements of slopes, cross-beam dimensions, and spacing were compared with the scarce data available in literature and put together to form empirical relations to predict flow characteristics in the engineering practice dealing with RCCB design, such as discharge limit, maximum flow, water depth, and friction factor. In particular, it shows that energy dissipation in roughened channels with cross beams increases approximately 30% in relation to channels where cross beams are not used. DOI: 10.1061/(ASCE)IR.1943-4774.0000457. (C) 2012 American Society of Civil Engineers.