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MISSING THE STORM: PREDICTING SEDIMENT EXPORT FROM BASEFLOW CONDITIONS IN LOW-ORDER LAKE SUPERIOR WATERSHEDS
Citation:
Taylor, D L., C M. Elonen, T. M. Jicha, AND L E. Anderson. MISSING THE STORM: PREDICTING SEDIMENT EXPORT FROM BASEFLOW CONDITIONS IN LOW-ORDER LAKE SUPERIOR WATERSHEDS. Presented at North American Benthological Society Annual Meeting, Vancouver, BC, June 6-10, 2004.
Description:
Midwestern streams export most of their annual sediment load during snowmelt and rainfall events, however measuring sediment export at peak stream discharges is not always possible. Watershed-level, riparian, and instream data were collected from 48 second and third order Lake Superior tributaries and used to predict sediment export from baseflow conditions. To separate natural from human-induced contributors to sediment export, Rosgen?s hierarchical stream type classification system was used as an integrator of stream geomorphological characteristics such as bedrock geology, width to depth ratio, entrenchment, and channel slope. Rosgen stream type, watershed area, visible bank erosion, woody debris, and instream shade accounted for 70 percent of the variation in total and small (under 2000 um) bedload mass exported. Export of gravel-sized bedload was predicted by watershed area, bank erosion, woody debris, and the percent of the watershed that had been logged in the past 15 years (r2 = .59). Median annual suspended sediment export was best explained (r2 = .53) by Rosgen stream type and percent agricultural land use in the watershed. Rosgen stream types proved useful for partitioning natural and human-caused sources of sediment export. Abstract does not necessarily reflect EPA policy.