The field of hydrology experienced its most dramatic period of development from the late 19th century to the mid-20th century. While the theory and equations used to estimate watershed runoff have remained relatively unchanged since that time, the availability of Geographic Information Systems (GIS) software and geospatial data has modernized the methods used to evaluate watershed characteristics and develop input parameters. Today’s hy...

Understanding how extreme storms and their precipitation are analyzed is critically important for dam design and dam safety. This webinar will detail the background of PMP and storm analysis starting with the earliest work completed by the US Weather Bureau (now National Weather Service) and continuing through current statewide and site-specific PMP work. Data and methods used to quantify rainfall spatially, temporally, and in magnitude will...

Changing demographics in the vicinity of dams have led to hazard creep in a number of dams worldwide. Many of these dams now have insufficient spillway capacity as a result of these changes in hazard classification from low to significant or high hazard. Stepped chutes applied to the embankment dams offer an advantage by providing increased spillway capacity. This webinar provides an overview on stepped chute research conducted at the USDA-Ag...

Failure mode evaluation or what now is more commonly referred to as potential failure mode analysis (PFMA) for dam safety has become routine practice for many in the profession. The process became more formally organized by the US Bureau of Reclamation in the early to mid 1990’s and gained wider industry exposure in the early 2000’s through the publication of FERC’s Engineering Guidelines, Chapter 14 – Dam Safety Perfor...

Failure mode evaluation or what now is more commonly referred to as potential failure mode analysis (PFMA) for dam safety has become routine practice for many in the profession. The process became more formally organized by the US Bureau of Reclamation in the early to mid 1990’s and gained wider industry exposure in the early 2000’s through the publication of FERC’s Engineering Guidelines, Chapter 14 – Dam Safety Perfo...

Introduction to Armoring Embankment Dams and Earth-Cut Spillways with ACBs Over the past 23 years numerous embankment dams and earth-cut spillways in the United States have been armored with Articulating Concrete Blocks (ACBs) to provide overtopping protection and to extend the life of the structures. With the current focus on evaluating and rehabilitating dams throughout the United States to pass increased design flows, the use of this const...

Labyrinth weirs are widely used in spillway rehabilitation to upgrade existing dams to meet updated spillway design flood criteria. In addition to increasing discharge capacity, these weirs are also well suited to regulating upstream pool elevations for flood control or at intake structures. The hydraulic design of a labyrinth spillway requires the consideration of complex flow characteristics and optimization of multiple geometric parameters...

Effective energy dissipation of flows from outlet works and spillways is an extremely important component in dam safety. Undersized or ineffective structures can lead to damage and failure, possibly endangering the dam or the flow channel and properties downstream. Generalized design criteria for many different types of energy dissipaters and/or stilling basins exist from several different government agencies, both federal and state (including...

The Webinar will have four ½ hour sessions and will begin with a brief review of the Hydraulics 101 Lectures. Uniform flow, specific energy, and gradually varied flow will be covered in the first session. Hydraulic modeling and water surface profile computations will be covered in the second session and geometric data requirements will be addressed in the third session. The final session will concentrate on the development of the Hydro...

The Hydrology 201 Webinar consists of four one-half hour segments. The first segment is a brief review of Hydrology 101 emphasizing some of the important hydrologic issues. The second segment will concentrate on the NRCS procedures to determine the loss rate function and the dimensionless unit hydrograph as it is utilized to transform excess rainfall into runoff. Different methods of determining time of concentration and lag time will be cove...