Flow dynamics at river channel confluences can be characterized by six major regions of flow stagnation, flow deflection, flow separation, maximum velocity, flow recovery and distinct shear layers. The dominant controls upon the magnitude of these regions are shown to be the junction angle and the ratio of discharges between the confluent channels. Through the combined use of scaled laboratory modelling and an analysis of field evidence, the dynamics of flow are found to produce a confluence morphology which consists of avalanche faces at the mouth of each confluent channel, a deep central scour and a bar within the separation zone. Tracing of sediment in both laboratory and natural channels reveals distinct sediment pathways within the junction which can be explained through the model of flow dynamics. A knowledge of confluence flow dynamics is important when assessing channel design criteria, junction bed morphology and ancient confluence sediments.