Abstract

This research examined the in-stream sediment sources derived from fluvial erosion for four 1-km2 headwater catchments in the Southern Sierra Critical Zone Observatory, which is co-located with the Kings River Experimental Watersheds. 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 channels. Sediment catch basins and turbidity measurements at the catchment outlets were used to measure the sediment production from the watershed. 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 0.9 m3 to 4 m3 per year for total headcut erosion and 1.4 m3 to 23 m3 per year for total bank erosion in the four study catchments. While magnitudes of erosion vary from year-to-year, the relative importance of the sources should apply to wet and dry years. Sediment-basin data, which cover a longer period, varied 10-fold interannually. Values suggest that much of the sediment is from in-stream sources. Finally, the scaled-down version of a linear bank-migration model, based on the sediment continuity equation, shows potential as a tool to estimate this key critical-zone process with relatively simple-to-measure model inputs.

Citation

Martin, S.E., Hunsaker, C.T., Bales, R.C. (2009): Sediment Sources in Four Small Mountain Streams in the Central Sierra Nevada, California . Fall meeting, American Geophysical Union, December 2009. 90(52). Abstract EP53D-0649..