From Desktop to Field: A Method for Hydraulic and Safety Evaluations at Low-Head Dams

Abstract Submission: Low-head dams, also referred to as run-of-river dams and weirs, are hydraulic structures that span the full width of a river, creek, or drainage path and typically are designed for uniform, shallow overtopping to raise upstream water surface depths without wholly preventing flow. Hydraulic conditions that develop downstream of low-head dams can be extremely hazardous and threaten the health and welfare of the public. Despite the prevalence of low-head dams throughout the United States (U.S.) and the extreme hazard associated with these structures, there is little public awareness of the threat that low-head dams pose to health and safety, and these hidden hydraulic hazards claim lives every year. This report presents a methodology developed by practicing engineers with more than a dozen combined safety evaluations at low-head dams to evaluate hydraulic conditions and the adequacy of safety plans. Steps for hydraulic and safety evaluations at low-head dams include 1.) pre-field (desktop) evaluations, 2.) in-field investigations and data collection, 3.) post-field hydraulic evaluations using a spreadsheet model developed by the U.S. Bureau of Reclamation (USBR), and 4.) documentation of results and recommendations for safety improvements.

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