Effects of natural and human driven watershed disturbance on sediment concentrations in two streams of central Vermont

Jaquith, Shayne
Joy Ackerman, PhD
Department of Environmental Studies
Sediment concentration and stream discharge were measured on the Stetson and Clay Brooks in the Mad River basin of Central VT during a period from June 15 through August 11. Intense precipitation on June 25 and a major flood event on June 27 triggered mass erosion and bank caving and altered the sediment/flow relationships of the two brooks. Following the flood sediment rating curves displayed greater slopes and intercepts than prior to the flood. Post flood sediment-discharge plots also displayed a significant increase in scatter which suggests that the two watersheds remain unstable and hysteresis is more prominent than prior to the flood. Sediment rating curves developed both before and after the flood show that for the range of flows observed, Clay Brook experiences greater sediment concentrations than Stetson Brook. Higher sediment concentrations and a weaker relationship between flow and sediment concentration in Clay Brook are attributed to bare soils in the watershed associated with unpaved roads and parking lots.

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