1. When ϕ=30–90° the confluence of open-channel flows is accompanied by the formation of an eddy zone on the downstream stretch of the main canal and zone of a high current velocity, when ϕ=30° the sizes of the eddy zones and channel deformation are considerable. 2. A backwater and some decrease of the current velocities are observed on the upstream stretch of the main channel. Channel deformation begins in the zone of confluence and reaches a maximum in the contracted section, channel deformation decreases with decrease of the angle of confluence. Intense deposition of sediments is observed in the eddy zone. 3. The proposed relations can be used when calculating the angles of confluence of channels in the indicated ranges of the main parameters.