Bottom rack intake is one of the most appropriate hydraulic structures for diverting water in steep rivers. The problems of corrosion and deformity of the bottom racks in the long term inspires a new system of bottom intake in which a filled trench of porous media replaces the bottom racks. In this article, the hydraulic characteristics of this intake are investigated in an experimental model designed in a two-storey channel. The lower channel is used to convey diverted water through the porous media, and the upper one is used to carry the remaining flow to downstream. Measurements of the diverted discharge were performed for different rates of flow, grain size distributions, and surface slopes of intake. Results show that the diverted discharge increases whenever the surface slope of bottom intake decreases, the inflow discharge increases and or coarse grains are used in the intake. The empirical equation for estimating the discharge coefficient (Cd ) of bottom intake shows that the Cd of porous media intake is about 0.1. To calculate the diverted discharge of intake, an empirical-theoretical relation has been proposed. The theoretical predictions in comparison with the experimental results have shown good consistency.

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