This study was designed to test the hypothesis that riverbank erosion processes altered with increasing distance from a river source. The River Swale, northern England, was monitored at nine sites throughout its 109-km length, from December 1995 – March 1998. Erosion pins, bank-edge surveying, and Photo-Electronic Erosion Pins (PEEPs) were used to determine rates and timings of erosion. The rates were compared against a range of environmental variables based on temperature, river stage, and precipitation at 14-day intervals for erosion pins and 15-minute intervals for PEEPs. This allowed processes of erosion to be inferred. Catchment erosion rates were modelled using quadratic equations, simulating a mid-basin peak of 3.58 m a\(^{-1}\). Rates of erosion were low upstream, 0.07 m a\(^{-1}\), and also downstream, 0.12 m a\(^{-1}\). Subaerial processes, especially frost action, dominated upstream. Fluvial entrainment was most influential mid-catchment. Mass failures were most efficient downstream, but were more frequent mid-catchment. Piping, sapping and cantilever failures did not follow the same trends and were modelled separately. The length of the erosion season increased downstream as the number of active processes increased.