Abstract: Some of the natural incised river channels have unique features in fluvial morphology and longitudinal profiles. In this study, the relevant mechanisms of fluvial morphology during incision and their influence on longitudinal profiles are investigated through field surveys, and the use of data analysis and geographic information system (GIS) techniques. Results show that there exists a loss and compensatory mechanism of sediment transport in response to riverbed incision, which is an important factor driving this type of river systems towards a state of equilibrium. After deepening, riverbed sediments consume more erosive energy and sustain high gradient channels, leading to special longitudinal profiles. River discharge and riverbed sediment are the dominant elements controlling the formation of longitudinal profiles. After introducing a dimensionless parameter derived from river discharge and riverbed sediment, the channel gradient and the new dimensionless parameter shows a good linear relationship.