experimental study of diverted discharge of bottom intakes with porous media in sediment flow

abstract bottom rack intake is one of the most popular structures used for diverting water in mountain region. corrosion and rotten problems of bottom racks inspire the introduction of a new system of bottom intake in which a porous media is replaced by the bottom rack. obviously, clogging and reduction of diverted discharge are the most important problems in this new system, too. in this paper, the effects of different media grain size, longitudinal slope, sediment grain size and flow discharge are investigated. results show that despite of clogging role of suspended sediments in porous media, using appropriate grain size and slope for the porous media, would attenuate the side effects of the problem. compare with clear water flow, the discharge reduction induced by clogging is not significant and efficiency of system in long time and no operation effort are confirmed. to recognize the effective parameters on infiltration resistance in porous medium intake an empirical theoretical formulation has been diverted from the darcy’s law in surface infiltration. the equation is found to be dependent on size ratio, reynolds number and hydraulic gradient. the theoretical predictions have been compared with experimental results, with good agreement.