Dr. David Topping is a Research Hydrologist with the US Geological Survey.

He did his undergrad at MIT, a masters and Phd at the University of Washington and has published >100 well cited peer review publications.

Dr Topping has worked with the USGS for >30 years but for the last 18 or so have been with the Grand Canyon Monitoring and Research Center in Flagstaff AZ where he has been one of the reasons that the Glen Canyon releases have become in one of the most ambitious and carefully measured protype sediment experiments in history.

And it is his teams extensive and precise measurements of these experiments and thoughtful analyses of those data that echoed through multiple aspects of my work in the years that followed.

I went back to the papers we talk about in this episode several times…

…when I was working on bed mixing algorithms in HEC-RAS

…and when I was working with the Corps’ Omaha district to restore sand bars on the Missouri river

…and when I was interpreting sediment time series, from the main Amazon tributaries…

I kept finding myself back in his literature.

His team’s work on processes that build and erode sand bars, his distinction between flow regulated and bed regulated transport, and his careful identification of the time scales and grain sizes at play when we think about ‘supply limitation’ and disequilibrium transport have all made their way into my work and my mental model of rivers.

You can find more of his work at these links:

https://www.usgs.gov/staff-profiles/david-j-topping

https://www.usgs.gov/centers/southwest-biological-science-center/science/river-sediment-dynamics

https://www.gcmrc.gov/discharge_qw_sediment/

This series was funded by the Regional Sediment Management (RSM) program.

Mike Loretto edited the first three seasons and created the theme music.
Tessa Hall is editing most of Season 4.

Stanford Gibson (HEC Sediment Specialist) hosts.

Video shorts and other bonus content are available at the podcast website:
https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast

...but most of the supplementary videos are available on the HEC Sediment YouTube channel:
https://www.youtube.com/user/stanfordgibson

If you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

This series was funded by the Regional Sediment Management (RSM) program.

Mike Loretto edited the first three seasons and created the theme music.
Tessa Hall is editing most of Season 4.

Stanford Gibson (HEC Sediment Specialist) hosts.

Video shorts and other bonus content are available at the podcast website:
https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast

...but most of the supplementary videos are available on the HEC Sediment YouTube channel:
https://www.youtube.com/user/stanfordgibson

If you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

Dr. Pierre Julien joined the Colorado State faculty almost 40 years ago, where he worked at CSU’s Engineering Research Center and Hydraulics laboratory.

His book, Erosion and Sedimentation, is one of my most common references, and several of the algorithms we have in HEC-RAS (particularly for mud and debris flows) come directly from this text. But while Dr. Julien’s textbook includes as many partial differential equations and tensors as any other hydraulics text – maybe more – it also includes “rules of thumb” scattered throughout.

I have integrated several of these nuggets of actionable, river mechanics wisdom into my field toolbox. They are heuristics I use regularly to quickly triage river processes and engineering proposals while standing next to a river or sitting in a meeting.

So I was curious if these rules of thumb would make an appearance in our conversation…and I was not disappointed. We do talk some theory. He shared a couple great metaphors that helped me visualize some of the complex theoretical principles of fluid mechanics better than I had going into the conversation.

But Dr. Julien does, also, intentionally develop these decision heuristics and rules of thumb, to help practitioners quickly rule in or rule out alternatives and they popped up throughout our conversation.

Dr Julien won the Einstein award in 2004 and the Hunter Rouse award in 2015 the American Society of Civil Engineers lifetime achievement awards for sediment and hydraulics respectively (which is apt as we ended up talking about both the men those awards were named after). He was also named a Distinguished Member of the American Society of Civil Engineers - their highest honor - in 2022.

Dr. Julien has completed projects world-wide with 50 different agencies including world bank and UNESCO and has guided at least 120 masters students and 44 PhDs from 16 different countries.

This series was funded by the Regional Sediment Management (RSM) program.

Mike Loretto edited the first three seasons and created the theme music.
Tessa Hall is editing most of Season 4.

Stanford Gibson (HEC Sediment Specialist) hosts.

Video shorts and other bonus content are available at the podcast website:
https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast

...but most of the supplementary videos are available on the HEC Sediment YouTube channel:
https://www.youtube.com/user/stanfordgibson

If you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248