AbstractThe sediment supply of a first‐order catchment in the Luxembourg Ardennes is considered. In the absence of overland flow the most important process of sediment supply is splash erosion. This is confined to areas of exposed mineral soil produced mainly by the burrowing activity of animals. The amount of splash erosion reflects not only burrowing but also the yearly cycle of litter‐fall and decay. The concentration of suspended material in the catchment river is not related to the discharge but in most cases to rainfall intensity. Turbidity measurements made at 1‐minute intervals showed a considerable degree of detail which illustrated the role of splash in supplying sediment to the river, although other processes can be important. The difficulty of estimating the output of material from a small catchment by means of a simple rating curve is stressed as is the need to consider slope and sediment supply processes in an ecological co