EMPIRICAL INVESTIGATION OF SETTLING VELOCITY IN OPEN CHANNEL

ABSTRACT Sediment deposition in urban open drain has reduced drastistically the hydraulic capacity of drain and has been identify as one of the factors causing flooding in urban areas. To reduce sedimentation, a constant minimum flow velocity is required in an open channel during rainfall. From the experimental work conducted in the trapezoidal open channel on empirical investigation of settling velocity in open channel. The following conclusion were drawn from the research. The higher the bedslope for all the sediment particles sizes, the higher the flow velocity. The maximum flow velocity was at 6.40 m/s for 2.38mm sediment particle size and minimum flow velocity at 6.19 m/s for 425um. It was observed that at lower flow velocity, sediment particle s was found deposited at the channel downstream end while at the upstream, no sediment deposition was observed. Furthermore, it was observed that as sediment mass concentration increases, the flow velocity decreases. At the channel downstream, it was observed that the sediment trap pit influences the flow velocity. From the experimental work. To avoid sediment deposition in trapezoidal flow open channel. maximum flow velocity of 6.40 m/s and minimum flow velocity of 6.19 m/s is recommended for use by engineers in urban open channel.