Water Resources Research Act Program

Details for Project ID KY_2025_Mahoney

Tracing sediment sources in flood-prone river-tributary confluences

Institute: Kentucky
Year Established: 2025 Start Date: 2026-01-01 End Date: 2026-12-31
Total Federal Funds: $20,000 Total Non-Federal Funds: $20,851

Principal Investigators: Tyler Mahoney

Project Summary: Riverine flooding is one of the costliest natural disasters in the United States. In particular, the confluence of larger rivers and smaller tributaries creates backwater zones where flooding is often pronounced. Sedimentation can exacerbate flood risks at these river-tributary confluences by decreasing available storage for stormwater retention. To mitigate these impacts, watershed managers must first identify the sources of sediment delivered to the confluence. Broadly, two sources of sediment contribute to deposition in river-tributary confluences: 1) sediment originating from the tributary and its watershed and 2) sediment that transports via backwater flows from the river. Understanding the degree to which each source contributes to sedimentation is critical for watershed managers when designing best management practices. This project will use sediment fingerprinting to investigate the sources of sediment delivered to two river-tributary confluences along the Ohio River in Maysville, Kentucky. The project will answer several questions, including: 1) which sources of sediment contribute most to river-tributary confluences along the Ohio River, 2) what role does tributary-confluence configuration play in sedimentation dynamics, and 3) to what degree does stormwater infrastructure (e.g., earthen dams, culverts, and flood walls) impact sedimentation in river-tributary confluences. Findings will support ongoing economic development surrounding river-tributary confluences in Maysville, as well as ongoing watershed planning efforts by the Kentucky Division of Water in the study watersheds. Furthermore, the project will fund a master's thesis, training of two undergraduate research assistants, and at least one peer-reviewed publication.