EXPRIMENTAL INVESTIGATION ON SEPARATION ZONE AT LATERAL INTAKES

摘要

Using lateral intake is a method of floodwater diverting. In arid and semi-arid areas, floodwater has large amount of sediment that will be carried into the intakes and decreases the channel conveyance. Sediment conveys into the intake and settles in the separation zone beside the upstream side of lateral channel. Sedimentation in separation zone reduces the conveyance of lateral channel, thus it is important to determine the length and width of separation zone. Several factors affect on separation zone such as the ratio of lateral intake discharge to main channel discharge and angle of lateral channel to the main channel flow direction. Experiments have been conducted for four degrees of diversion channel. Slope and width of main channel, width of lateral channel and bed material of main channel are constant in all experiments. In each lateral channel intakes, ten experiments have been done. The velocity vectors (magnitude and direction) into the lateral channel have been measured. The pattern of sedimentation has been determined using bed topography. It was found that the separation zone in the lateral channel related to the ratio of lateral flow to main channel flow and angle of intakes. With increasing of lateral flow, the length and width of separation zone decrease and with decreasing angle of lateral intake, the length of separation zone increase and the width of separation zone decrease. For the length and width of separation zone some equation have been derived.