A Tool to Identify Dangerous Conditions at Low-Head Dams

ABSTRACT ONLY - Low-head dams present dangerous conditions for river users when a submerged hydraulic jump produces strong reverse-flow currents downstream from the dam. A national task force is using aerial imagery to identify potentially dangerous low-head dams across the U.S., but a more definite determination requires field data and analysis of hydraulic conditions for a range of flow rates. To aid this effort, a straightforward spreadsheet application has been created to identify the flow rates at which strong reverse-flow will occur, based on experimental work performed by Hans Leutheusser and colleagues in the early 1990s. The analysis considers the dam geometry and the tailwater conditions imposed by the downstream channel to identify the limits of strong reverse flow conditions. The spreadsheet is valuable for analysis of specific sites, and general application shows that most low-head dams create dangerous conditions for a significant range of flow.