Predicting bedload transport for restoration of upper Spanish Creek, California

River restoration often requires sediment transport data as a fundamental design parameter. Acquiring this data is very difficult, especially in mountain gravel-bed rivers. Application of portable bedload traps and a numerical model to quantify bedload transport for restoration of Spanish Creek, California is the focus of this study. Restoration is needed because debris from hydraulic mining in the 1880's has been deposited in the Spanish Creek river valley, burdening the river with excess sediment.;River bed sampling indicated that the bed surface is completely armored with a mean particle diameter of 35 mm and a much finer subsurface. Bedload data were collected during the 2005 spring snowmelt using five portable bedload traps. Portable bedload traps are effective tools to measure bedload transport, but their accuracy is limited by trap dimensions and spacing, stability during high flows, accessibility for monitoring, and intensity of monitoring. The bedload traps are modified from the original design by Bunte et al. to increase durability in order to continuously sample for the entire spring snowmelt. Bedload data are used to calibrate the Parker (1990) surface-based fractional bedload transport equation for Spanish Creek. The EnSed2D numerical model employs the Parker equation and is used to simulate stream morphodynamics for a bankfull scenario. Model predictive results are used to quantify rates of bedload transport and bed elevation change in all reaches of Spanish Creek. The best location to detain/store sediment to achieve the desired restoration goal is identified and recommendations will be incorporated into designs for restoration.