Location
Atlanta, GA
Presentation Type
Presentation
Start Date
10-7-2025 9:25 AM
Description
During extreme flood events, floating trees (driftwood) can pose serious risks to the safety and operation of dams. In upgrading an existing dam, a piano key weir (PKW) is introduced to replace the aging embankment dam and to increase the discharge capacity of its gated spillway. This upgrade necessitates a detailed understanding of driftwood behavior at both discharge structures, which differ significantly in design and operating conditions. To investigate this, hydraulic model tests were conducted using small, freshly cut trees—some with branches and roots—to simulate natural trees moving towards the dam. The results indicate that tree accumulation at the gated spillway or PKW depends on flow discharge, cross-sectional position in the reservoir and water levels. Blockage of the gates—or simultaneous blockage of both the gates and the PKW—causes a greater rise in reservoir water level than blockage of the PKW alone. However, the rise is still limited. The study highlights that the combined use of the PKW and the gated spillway is cost-effective, as they complement each other in managing driftwood and mitigating water-level rise
Included in
Floating Trees at Co-Existing PKW & Gated Spillway
Atlanta, GA
During extreme flood events, floating trees (driftwood) can pose serious risks to the safety and operation of dams. In upgrading an existing dam, a piano key weir (PKW) is introduced to replace the aging embankment dam and to increase the discharge capacity of its gated spillway. This upgrade necessitates a detailed understanding of driftwood behavior at both discharge structures, which differ significantly in design and operating conditions. To investigate this, hydraulic model tests were conducted using small, freshly cut trees—some with branches and roots—to simulate natural trees moving towards the dam. The results indicate that tree accumulation at the gated spillway or PKW depends on flow discharge, cross-sectional position in the reservoir and water levels. Blockage of the gates—or simultaneous blockage of both the gates and the PKW—causes a greater rise in reservoir water level than blockage of the PKW alone. However, the rise is still limited. The study highlights that the combined use of the PKW and the gated spillway is cost-effective, as they complement each other in managing driftwood and mitigating water-level rise