Sediment Budget Approach to Evaluating Legacy Deposits on Missouri Ozark Floodplains

Authors: Katy Reminga*, Missouri State University
Topics: Geomorphology
Keywords: sedimentation, deposition, rates, legacy sediment, floodplains, channelization
Session Type: Poster
Day: 4/12/2018
Start / End Time: 8:00 AM / 9:40 AM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded

Hydrologic disturbances due to land use and climate effects can disrupt river form and increase sediment transport. Ozark streams have been affected by accelerated sediment delivery and gravel bar deposition in main channels since early European settlement in the late 1800’s. However, the fate of fine-grained sediment released by historical soil and channel erosion and its potential for storage in floodplain legacy deposits has not been addressed. Big Barren Creek watershed (191 km2) drains the Salem Plateau in the Ozark Highlands of south eastern Missouri. It is hypothesized that episodes of legacy deposition may have occurred within this region in association with periods of (i) widespread logging of pine forests (1880-1920) and (ii) channelization of the stream for flood control along bottomland segments since 1960. Stratigraphic analysis is used to evaluate the origin and age of floodplain deposits. Further, stratigraphic indicators will be used to create a sediment budget framework to identify historical sediment storages and evaluate the impact of recent channelization (straightening and deepening of the stream) on the geomorphic stability of the headwaters of Big Barren Creek. Floodplain samples will be collected at locations above, within, and below a channelized segment to examine sediment texture, organic matter, Cs-137, and magnetic susceptibility profiles and assess buried soil and root crown elevations. Preliminary results using Cs-137 trends in floodplain cores indicate post-1963 sedimentation rates in upper Big Barren occurring at an average of 0.28 cm/yr and sedimentation rates in middle Big Barren at a rate of approximately 0.5 cm/yr.

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