The functions of the diversion channel are usually disturbed by sediment erosion and deposition.Considering the effects of unsaturated sediment flow and narrowed cross section the diversion channel is enormously eroded.The discharge capacity,however,is deteriorated for the local deposition which lessens the water depth to satisfy the minimum navigable flow rate.In this study,the alternative diversion channel with unsaturated sediment flow at Hanjiang River,China,was taken as an example.The impacts of bed morphology for flood events and normal flow conditions were analyzed.The results show that the consideration of bed morphology is essential to design the diversion channel.Even for the unsaturated and eroded channel,the local deposition can reduce the water depth and restrict the navigable requirement under normal flow conditions. The functions of the diversion channel are usually disturbed by sediment erosion and deposition .Considering the effects of unsaturated sediment flow and narrowed cross section the diversion channel is enormously eroded.The discharge capacity, however, is deteriorated for the local deposition which lessens the water depth to satisfy the minimum navigable flow rate. In this study, the alternative diversion channel with unsaturated sediment flow at Hanjiang River, China, was taken as an example. The impacts of bed morphology for flood events and normal flow conditions were. The results show that the consideration of bed morphology is essential to design the diversion channel. Even for the unsaturated and eroded channel, the local deposition can reduce the water depth and restrict the navigable requirement under normal flow conditions.