FACTORS INFLUENCING SEDIMENT TRANSPORT IN LOCUST CREEK, EVANSVILLE, INDIANA

Geomorphologic research on Locust Creek, a small (45 km2) watershed in north central Vanderburgh County near Evansville, Indiana, focused on sediment transport as related to variations in discharge. Of specific interest were the variations in bedload (Qbsed) transport compared to suspended sediment (Qssed) under low flow and high flow characteristics. Discharge and sediment load (Qbsed, Qssed) data were collected at two sites, and upstream results (site 1) compared to those collected from downstream (site 2). Bedload transport during low flow (0.45 m3/s) averaged 907.2 g/day at site 1 and 7,366.01 g/day at site 2 under similar low flow conditions (0.226 m3/s). A representative high flow condition (1.32 m3/s) bedload averaged 12,586.2 g/day at site 1 and 92,959.425 g/day at site 2, under similar high flow conditions (2.53 m3/s). Suspended sediment transport at site 1 was 3,089,016 g/day under low flow and 6,030,858.24 g/day under high flow. At site 2, the suspended sediment load was 11,893,139.71 g/day and 104,032,304.6 g/day under low and high flow, respectively. Changes in Qssed and Qbsed correlate with increases in precipitation, and Q, both of which affect flow velocity and the ability of the stream to entrain and transport sediment. Differenced in Qsed between sites are attributed to increased drainage basin area, increased discharge, and an increase in channel dimensions to accommodate the aforementioned variables.