Presentation Title

Flood-event sediment distribution within oxbow lakes in the Pee Dee River, SC floodplain

Presentation Type

Presentation

Full Name of Faculty Mentor

Zhixiong Shen, Marine Science

Major

Marine Science

Presentation Abstract

Extreme flooding is one of the costliest natural disasters happening around the world today and its effects have been intensifying over the past century. To produce reliable paleoflood record and study its long-term variability, the spatial distribution of flood-event deposits and their hydrodynamic and geomorphic controls in river floodplains needs to be better understood. The purpose of this project was to identify those controls and the usefulness of sedimentary paleoflood records from floodplain oxbow lakes. This was accomplished by taking sediment core samples from two oxbow lakes in the Pee Dee River, SC floodplain with a piston corer. The core sediments were examined in detail and analyzed with a CILAS 1190 laser-diffraction particle-size analyzer to identify and study the coarse event deposits of the Hurricane Florence (2018) flood, the largest in the area since 1948. The coarsest and thickest sediment facies near the core top was assumed to be Florence deposits. Each lake exhibited dramatically different degrees of facies presence and thickness, presumably due to river morphology and the availability of sand in that area. Additionally, a correlation was identified between the thickness of the event deposits and the core's proximity to the river; where cores collected from the distal side of the lake showed minimal down-core variation in mean sediment coarseness and cores proximal to the river exhibited thick facies of coarse sediment that were clearly identifiable as paleoflood events. The information gained here is invaluable for better analysis of sedimentary records of flood-event deposits.

Location

Room 2 (BRTH 112)

Start Date

12-4-2022 4:50 PM

End Date

12-4-2022 5:10 PM

Disciplines

Oceanography

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Apr 12th, 4:50 PM Apr 12th, 5:10 PM

Flood-event sediment distribution within oxbow lakes in the Pee Dee River, SC floodplain

Room 2 (BRTH 112)

Extreme flooding is one of the costliest natural disasters happening around the world today and its effects have been intensifying over the past century. To produce reliable paleoflood record and study its long-term variability, the spatial distribution of flood-event deposits and their hydrodynamic and geomorphic controls in river floodplains needs to be better understood. The purpose of this project was to identify those controls and the usefulness of sedimentary paleoflood records from floodplain oxbow lakes. This was accomplished by taking sediment core samples from two oxbow lakes in the Pee Dee River, SC floodplain with a piston corer. The core sediments were examined in detail and analyzed with a CILAS 1190 laser-diffraction particle-size analyzer to identify and study the coarse event deposits of the Hurricane Florence (2018) flood, the largest in the area since 1948. The coarsest and thickest sediment facies near the core top was assumed to be Florence deposits. Each lake exhibited dramatically different degrees of facies presence and thickness, presumably due to river morphology and the availability of sand in that area. Additionally, a correlation was identified between the thickness of the event deposits and the core's proximity to the river; where cores collected from the distal side of the lake showed minimal down-core variation in mean sediment coarseness and cores proximal to the river exhibited thick facies of coarse sediment that were clearly identifiable as paleoflood events. The information gained here is invaluable for better analysis of sedimentary records of flood-event deposits.