ABSTRACTWithin a 13 km reach of the lower course of the River Culm, Devon, UK, the river has a well-developed flood-plain which is frequently inundated at times of high flow. Detailed records of suspended sediment load obtained from upstream and downstream gauging stations indicate that approximately 28% of the upstream load may be deposited within this reach. Direct measurements of floodplain sedimentation using‘plastic grass’sediment traps evidence both macro-and microscale spatial variations in deposition which can be related to the duration of inundation, the topography of the floodplain surface and the flow velocity of the inundating water. Rates of deposition have been estimated from conveyance losses and these have been compared with data obtained from the sediment traps. Average rates of approximately 490 g m-2(0.49 mm year-1) are indicated. A comparison of the characteristics of storm and floodplain sediment indicated that conveyance losses are associated with a preferential loss of the coarser fractions, although appreciable deposition of the clay fraction also occurs.