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Changes in Stream Morphology and Storm Transport of Seston Following Watershed Disturbance

1987; University of Chicago Press; Volume: 6; Issue: 1 Linguagem: Inglês

10.2307/1467519

1937-237X

Stephen W. Golladay, Jackson R. Webster, E. F. Benfield,

Freshwater macroinvertebrate diversity and ecology

Surveys of stream morphology and measurements of particulate organic matter (seston) transport were made in four streams to examine response to forest disturbance. Seston was sampled during baseflows and stormflows in streams draining an 8-year-old clearcut, a 25-year-old clearcut, and two reference watersheds at Coweeta Hydrologic Laboratory in the southern Appalachian Mountains of North Carolina. Surveys of stream morphology indicated that there were fewer debris dams and organic matter accumulations in disturbed streams. Baseflow seston concentrations varied seasonally, ranging from 0.5 to 1.0 mg/L in winter and from 3.0 to 7.0 mg/L during summer. Baseflow seston concentrations did not differ consistently between streams. In all streams, seston concentration increased with increasing discharge during storms and was positively correlated with the rate of change of discharge during rising flows. Seston concentrations decreased during peak flows and gradually declined as discharge returned to baseflow. Average seston concentrations during storms were generally highest in streams draining disturbed watersheds, and export (g AFDW transported/m 2 stream channel) was significantly higher in streams draining disturbed watersheds. Storm transport varied with season, storm intensity, and storm duration. Our results show that baseflow seston concentrations in streams draining disturbed areas may return to normal levels within a few years following disturbance; however, concentrations during storms may remain elevated for many years.