Sediment Production in a small Appalachian Watershed during Spring Runoff: The Eaton Basin, 1970–1972

This report describes work in an IHD Representative Basin in the Quebec Appalachians, the Eaton River Basin (86 km 2 in area), upstream from Randboro. The Basin is dominantly forest-covered, contains no large settlement, and, in general, shows little human disturbance that might affect sediment production. The suspended load of the Eaton River was studied in detail during the spring runoff periods of 1970 and 1971; available long-term discharge data indicate these to be representative of present-day conditions. Sediment transport rates are well below capacity and sediment yields are lower than might have been expected from the Langbein-Schumm data in the United States. Suspended sediment originates primarily from scour of the banks of the channel network, and concentrations show a systematic increase with basin area (or distance downstream), quite unlike previous data from the midwestern United States. The sediment rating curve approach is a very good predictor of sediment transport rates, although because of the differences in hydrograph type, there is a large difference between the equations for the 1970 and 1971 spring floods. This difference, and residuals from the sediment rating curves, are considered in a simulation model of sediment production from bank erosion based on the changing shear resistance of bank sediment during a fluctuating hydrograph.