UC Merced

This research examined the in-stream sediment sources for four 1 km² headwater catchments in the central Sierra Nevada, California. Erosion of material from two major sediment sources within headwater channels was estimated: headcut erosion and bank erosion. Repeat surveys of channel headcuts were conducted; measurements of channel geometry were used in conjunction with bank erosion measurements in a bank migration model to estimate bank erosion for the length of the channel. High amounts of variability were found in the measured stream parameters and eroded volumes both within each catchment and across the four catchments, but values were within one order of magnitude for all four study watersheds. Results also showed that though migration rates were similar in headcuts and bank bends, bank erosion totals were much higher than headcut erosion totals for three of the four catchments and roughly equal in the remaining catchment. Values ranged from 0.89 m3 to 4.24 m3 per year for total headcut erosion and 1.43 m³ to 23.61m³ per year for total bank erosion in the four study catchments. Finally, a scaled down version of a linear meander migration model based on the sediment continuity equation, shows potential as a tool for managers to estimate bank erosion, as it appears to give reasonable values using a few relatively simple to measure model inputs.