Using Sediment Particle Size Class Analysis to Better Understand Urban Land-Use Effects
Jason A. Hubbart

Abstract
A nested-scale experimental watershed study design was used to demonstrate rainfall-runoff and sediment particle size class variability in a representative urbanizing watershed in central Missouri, USA. On average, sediment particle size classes were almost twice as large (2.0 to 500μm size range) in headwaters, relative to an urban setting. Eighty percent of total sediment in the headwaters was between 216 and 357 μm but only 40% in the urban setting. A 13.2 mm rainfall event resulted in a doubling of streamflow 1.4 m3/s to 2.9 m3/s but resulted in more than quadrupling the concentration of particle size classes ranging from 0.2 to 67.65 μm. Results illustrates the need to better understand fine particle suspended sediment concentrations in surface runoff from urbanizing systems relative to that flowing from agricultural and/or forest environments. Future work holds important implications for understanding the effects of urbanization on sediment loading, aquatic ecosystem health, and water quality.

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