Long-term reach-scale suspended sediment budget of a small creek with cohesive banks

Authors: AL-GHORANI, NISREEN - University Of British Columbia; HASSAN, MARWAN - University Of British Columbia; Langendoen, Eddy

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/26/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sediment budgets play an important role in determining and managing the physical integrity of stream systems. However, quantifying sediment inputs from all sediment sources and by size fraction is problematic when both land use and reach geometry are not static. ARS researchers at Oxford, MS, in collaboration with scientists from the University of British Columbia, Canada, used a comprehensive 20-year record of land use, rainfall, stream flow, and suspended sediment concentration collected by the USDA, ARS, National Sedimentation Laboratory in the Goodwin Creek Experimental Watershed in combination with surveyed reach geometry and computer simulation to study sediment budget dynamics of fine-grained sediments (clay and silt) during the period 1982-2002. For this evolving channel system with cohesive banks, medium and long duration floods had a greater effect on fine sediment dynamics than large, short duration events as streambanks were a major source of the fine sediment. However, the effectiveness of individual flood events is strongly influenced by the preceding stability state of the streambank. The study shows that sediment budgets, which adequately quantify sediment inputs from all sources, can help evaluate the impact of land management practices on sediment transport processes, and therefore identify appropriate policies for future land use while mitigating environmental consequences.

Technical Abstract: Constructing long-term sediment budgets for evolving channels with cohesive banks has long been a challenging task. In this study, a 20-year (1982-2002) suspended sediment budget of the Goodwin Creek (GC), Mississippi, USA was developed using a combination of high-quality sediment measurements and computer-model simulations. We explored the temporal patterns of in-channel suspended sediment dynamics and examined their link to variable flow conditions. Medium and long duration flow events were found to have a greater influence on fine sediment storage within the GC than large, short duration events. Their effectiveness, however, is strongly influenced by the preceding channel’s conditions and the stability state of the banks. Throughout the study period, large and frequent gains in fine sediment storage modulated the streambed degradation caused by substantial loss events. Our findings have direct implications for river restoration projects and emphasize the need to account for these flows in similar channels.