Technical Remarks on Sediment Measurement at the Outlet of Small Watersheds

Soil erosion and sedimentation measurements and evaluation of the temporal and spatial data thus obtained are crucial for advancing the knowledge on soil erosion, evaluating relevant models, and designing soil erosion experiments. Extensive temporal changes in erosion and sediment yields, particularly in small watersheds, require special technical provisions to ensure accurate records. Based on the existing records, maximum events, or even a single one (with a high return period), play an important role in altering average sediment yields in river basins. It is, therefore, necessary to collect long-term data in order to derive a reliable average value for sediment yield under natural conditions. The present paper explores such technical considerations in measuring sediment yields in small experimental watersheds. For this purpose, two simple and automatic sediment samplers and a flow divider are introduced for measuring suspended sediments. It is also shown that concrete tanks and small reservoir dams need to be constructed at the outlets of the experimental watersheds. Finally, different methods used for measuring total load (including bed and suspended loads) are described.