Characterization of Erosion Rates From Two First-Order Watersheds Near Yuma, AZ: Towards an Enhanced Understanding of Alluvial Fan Dynamics
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Authors
Thomas, Darren Beck
Issue Date
2023
Type
Thesis
Language
Keywords
Alternative Title
Abstract
Timing and rates of sediment production and transport in alluvial environments are not well understood. Particularly, are these systems limited by sediment production rates or by sediment transportation rates? Beryllium-10 (10Be) quantification was used to determine long-term bedrock erosion rates, catchment-average erosion rates, and paleo-erosion rates in the Muggins Mountains, an arid drainage basin in southwestern Arizona. Comparing erosion rates at different points in the alluvial system tests for variance in time between sediment production, transportation, and deposition and further allows for characterization of drivers of landscape change. 10Be data indicate that (1) the basins are in dynamic steady state with respect to sediment production and transport, (2) average erosion rate decreases with distance from the sediment source, (3) average erosion rate for each basin varies with time. Findings suggest that rates of sediment transport downstream vary on timescales governed by atmospheric circulation patterns rather than glacial and interglacial cycles, and that the likely primary mechanism of sediment generation in the Muggins Mountains may be salt shattering on different slope aspects of the highlands.