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INSTRUCTOR:
F. Douglas Shields, Jr., Ph.D., P.E., D.WRE, F.EWRI, F.ASCE
Purpose and Background
Low head dams are defined as dams < 15 ft high with overflow weirs that span the entire width of the downstream channel. Often their weirs are ungated, free overfalls. Numbering more than 10,000 in the U.S., low head dams are ubiquitous across the landscape, often constructed decades ago for water-powered mills, hydroelectricity, water supply, irrigation diversions or other purposes. Under certain flow conditions, the hydraulic jump that forms below the dam becomes submerged in the tailwater, creating a reverse roller that is powerful enough to trap swimmers. Drowning deaths below low head dams are shockingly common, with at least 1,400 known fatalities. Drawing on previous analysis by others, engineers with the US Bureau of Reclamation have developed a tool (Excel file) for analyzing the hazard a given dam poses across a range of discharges.
Benefits and Learning Outcomes
Upon completion of this course, you will be able to:
- List the main dangers low head dams pose to boaters and swimmers
- Identify sources of information about low head locations and low-head-dam-related drownings
- Use tools available in the public domain to analyze the hydraulics of a given low head dam tailwater across a range of discharges
- Interpret and communicate results of their analysis to non-engineers
Assessment of Learning Outcomes
Students' achievement of the learning outcomes will be assessed via a short post-assessment (true-false, multiple choice and fill in the blank questions).
Who Should Attend?
Anyone who works with or in:
- Water Resources
- River Engineering
- Hydraulic Structures
- Safety
Or holds a position in the following:
- Hydraulic Engineer
- Public Works Manager
- Government Service
Outline
- Introduction
- Low head dam definitions and examples
- Numbers and distribution of low head dams in the U.S.
- State inventories
- National inventories
- Fatalities associated with low head dams
- Low head dam hydraulics
- Hydraulic jumps (review)
- Four states for hydraulic jumps
- Reverse current equations derived by Leutheusser
- Safety limits developed by Olsen et al.
- Low head dam hydraulic analysis
- CFD analyses
- Wahl and Svoboda spreadsheet
- Complications and exceptions
- Modifications of low head dams to ensure safety
- Summary
How to Earn your CEUs/PDHs
This course is worth .1 CEUs /1 PDHs. To receive your certificate of completion, you will need to complete a short on-line post-test and receive a passing score of 70% or higher within 365 days of the course purchase.
How do I convert CEUs to PDHs?
1.0 CEU = 10 PDHs [Example: 0.1 CEU = 1 PDH]