Thursday, October 21, 2021

Visualizing River Processes: Engaging Ways to Communicate with Stakeholders

9:00 a.m. – 12:00 p.m.

Careful consideration of riverine systems, functions, and processes is paramount for both the safe and resilient design of transportation systems and the preservation or enhancement of the natural environment. Yet many transportation project team members and partners do not have the requisite knowledge, tools, and confidence to practically apply key river science concepts to their projects. This workshop will demonstrate fun, engaging, and accessible technologies and techniques for teaching basic river concepts to novice learners. One such technology is the FHWA Stream Table, a hands-on model to simulate river, floodplain, and infrastructure interactions. The Stream Table uses small-scale models of bridges, culverts, bank protection, and other infrastructure components to visualize key concepts such as points of soil erosion and how rivers meander and migrate. The presenters will also discuss the use of virtual reality and 360-degree video river visits as training tools.

Instructors:

• Eric Brown, Senior Hydraulic Engineer, U.S. Federal Highway Administration
• Laura Girard, Senior Hydraulic Engineer, U.S. Federal Highway Administration
• Kornel Kerenyi, Hydraulics Research Program Manager, U.S. Federal Highway Administration
• Nathan Tsou, Research Engineer, Genex Systems
• Christoph Zuelow, Research Engineer, Genex Systems

Observation Method for Scour

10:00 – 11:30 a.m.

Bridge scour is the number one cause of bridge collapse in the USA yet the existing guidelines are felt to be excessively conservative. These apparently conflicting statements are due to the fact that most bridge foundations designed before 1987 did not consider scour as part of the design. The Observation Method for Scour (OMS) was developed to address the conservatism inherent in the current procedures by relying significantly on past observations at the bridge. The OMS works in four steps. Step 1 consists of collecting the maximum observed scour depth at the bridge, Zmo. Step 2 consists of finding out what is the biggest flood velocity Vmo that the bridge has been subjected to since its construction. Step 3 answers, by using an extrapolation function, the question: what will be the scour depth Zfut if the bridge is subjected to a major flood velocity Vfut. Step 4 is a comparison between Zfut and the allowable scour depth Zall for the foundation. This short course presents the detailed approach of using the observation method for scour. Eleven bridge scour case histories in Texas and in Massachusetts are presented where the OMS was applied and the results are used to compare predicted and measured values of Zfut for both the OMS and the current FHWA guidelines. The advantages and drawbacks of the OMS are outlined in a final section.

Instructor:

• Jean-Louis Briaud, Distinguished Professor, Texas A&M University, President of ASCE

Debris Flow Analysis with HEC-HMS and HECRAS

• Part 1: Debris Yield Analysis Using HEC-HMS (2-hr);
• Part 2: Non-Newtonian Mud and Debris Transport Using HEC-RAS (2-hr)

1:00 – 5:00 p.m.

The USACE Hydrologic Engineering Center (HEC) has added debris yield and flow capabilities to its popular hydrologic and hydraulic software. HEC’s Hydrologic Modeling System (HECHMS) can now compute debris yield and the River Analysis System (HEC-RAS) can simulate the non-Newtonian fluid physics of mud and debris flows associated with post-wildfire events and mine-tailing dam breaches.

Part 1: Debris Yield Analysis Using HEC-HMS

HEC-HMS version 4.8 includes five debris yield methods; LA Debris Method EQ.1, LA Debris Method EQ 2-5, Multi-Sequence Debris Prediction Method (MSDp.m.), USGS Long-Term Debris Model, and U.S. Geological Survey (USGS) Emergency Assessment Debris Model that simulate the post-wildfire debris yield processes from burned watershed areas. The overall goal of Part 1 of the short course is to use the debris yield methods in HEC-HMS for debris yield calculation from burned watershed areas. The first objective is to understand sediment and debris yield process and the empirical debris yield equations implemented in HEC-HMS (Lecture). The second object is to develop debris yield model including parameter estimation and calibration using HEC-HMS (Case Study Demonstration).

Instructor:

• Jang (Jay) Pak, Senior Research Hydraulic Engineer, Hydrologic Engineering Center, U.S. Army Corps of Engineers (USACE)

Part 2: Non-Newtonian Mud and Debris Transport Using HECRAS

The second session will use debris yield results from HEC-HMS as boundary conditions for the mud- and debris-flow simulations in HEC-RAS. This session will introduce the non-Newtonian physics that HEC-RAS uses to simulate these high-concentration events and go through the interface and input parameters required to model these flows in HEC-RAS. Participants will learn how to parameterize a oneor two-dimensional HEC-RAS model to compute the effects of post-wildfire or mine-tailing debris on flood depth, flood warning time, and mapping the debris inundation floodplain.

Instructor:

• Stanford Gibson, Senior Research Hydraulic Engineer, Hydrologic Engineering Center, U.S. Army Corps of Engineers (USACE)

Bridge Scour Power Hour

1:00 – 5:00 p.m.

Understanding how to correctly evaluate bridge scour is paramount to designing foundations that are safe and resilient throughout the design life of a bridge. The recent release of the Tech Brief “Hydraulic Considerations for Shallow Abutment Foundations” and the FHWA’s continued emphasis on 2D modeling has allowed many designers a more detailed and accurate understanding of the scour computation process. Many engineers have discovered that, though their hydraulic modeling and scour computation procedure generate scour depth results, they lack a thorough understanding of the concepts and how computational parameters affect the results. These new insights have led the FHWA Resource Center Hydraulics Team to initiate novel opportunities for detailed instruction on evaluating bridge hydraulics and scour. Participants in this workshop will have a ‘refresher’ on scour, highlighting the best practices of extracting hydraulic variables for computing scour and more efficiently applying the results. They will also learn about new tools for computing bridge scour with 2D hydraulic models that provide more accurate scour computation results. After completing this workshop participants will have a better understanding of the scour evaluation process and an improved confidence in their total scour estimates.

Instructors:

• Scott Hogan, Senior Hydraulic Engineer and Geotechnical & Hydraulic Engineering Team Leader, U.S. Federal Highway Administration
• Laura Girard, Senior Hydraulic Engineer, U.S. Federal Highway Administration