Anthropogenic disturbance, geomorphic response, and sediment budget in a small Missouri Ozarks watershed

Authors: Robert Pavlowsky*, Missouri State University, Katy Reminga, Missouri State University, Grace Roman, Missouri State University
Topics: Geomorphology, Water Resources and Hydrology, Anthropocene
Keywords: fluvial geomorphology, legacy deposits, sediment budget, Ozark Highlands
Session Type: Paper
Day: 4/10/2018
Start / End Time: 8:00 AM / 9:40 AM
Room: Balcony K, Marriott, River Tower Elevators, 4th Floor
Presentation File: No File Uploaded

Human modifications of stream systems often result in channel instability and sediment problems. However, the resilience of channels under a specific disturbance regime can vary by geology and land use. This study evaluates historical changes in channel form and stability in upper Big Barren Creek (10 km2) which drains national forest land in the Ozark Highlands of southeast Missouri. The purpose of this study is to evaluate the role of human activities on present-day channel and floodplain form and sedimentation using historical aerial photographs, stratigraphic analysis, and recent channel surveys. Pre-settlement channels were wide and shallow so that floods spread out across the valley floor. To reduce flood frequency on pastures, riparian landowners channelized the creek in the 1970s which caused head cuts to migrate upstream and sediment pulses to release downstream. A sediment budget shows that almost all excess sedimentation below the channelized segment, including legacy floodplain deposits, was generated by head-cutting, bed winnowing, and excavation operations. In fact, most of the drainage area above the disturbed segment is presently stable with low sediment yields even though it was cleared by logging between 1880 and 1920.

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