In the United States, we expect clean water from our taps, but the experiences of Jackson, Mississippi over the last several years are a reminder that we cannot take that water for granted. Since 2020, aging infrastructure, chronic underfunding, and extreme weather have placed the city in a state of emergency. Residents are often under boil water notices, if they have water pressure at all. In this video, Grady from Practical Engineering dissects the engineering side of this crisis and what’s needed to keep a city’s residents supplied with clean water. Check out the video’s links for more on the racism and politics that impact the crisis. (Video credit: Practical Engineering)
Tag: civil engineering
How Spillway Gates Work
Dams and reservoirs need a way to control their water level, and for many, that’s managed using spillway gates. In this video, Grady from Practical Engineering introduces several types of spillway gates, including their advantages and disadvantages. As always, he’s got neat tabletop demonstrations of each type, and he digs into the practical issues engineers face when building, maintaining, and repairing these critical pieces of infrastructure. (Image and video credit: Practical Engineering)
Yellowstone Flooding
In June of 2022, the area around Yellowstone National Park saw catastrophic flooding. The combined effects of rainfall and snowmelt overwhelmed waterways and washed out many roads and other structures in and around the park. In this video, Grady from Practical Engineering breaks down the floods and their aftermath, including how the area can be rebuilt. His depiction of the flood, from an engineering standpoint, is especially helpful, as he illustrates conditions across the park using flow sensor data. It helps explain the damage and gives viewers a sense for how engineers monitor and analyze these events. (Image and video credit: Practical Engineering)
When Reservoirs Run Dry
With the ongoing megadrought in the U.S. Southwest, more and more reservoirs are reaching historic low water levels. So it’s worth asking: what happens when a reservoir runs dry? And what, exactly, does a reservoir do in the first place? In this Practical Engineering video, Grady tackles both questions and takes a look at the many disciplines — beyond just civil engineering — that go into making a functional reservoir. (Image and video credit: Practical Engineering)
Treating Water
In an ongoing series, Practical Engineering is looking at how civil engineers deal with sewage and wastewater. In this video, Grady looks at how wastewater gets treated to remove contaminants. Where possible, engineers use gravity to do this job, building infrastructure that slows the flow down and lets gravity make heavier particles settle out. Of course, sometimes gravity alone doesn’t act quickly enough, in which case engineers use a little extra help in the form of chemicals that can neutralize particles’ electric charge and help them clump together and settle faster. Check out the full video for a tour of how wastewater gets processed. (Image and video credit: Practical Engineering)
How Wells and Aquifers Work
When rain falls, some of that water turns into run-off in storm systems but much of it seeps into the ground. What happens to that water? In most places, it joins the local aquifer, infusing the spaces between soil particles underground. In this video, Grady takes us through some of the interactions between surface water, aquifers, and the wells we use to access water underground. He’s even built some great demonstrations to show how aquifers and surface water like rivers pass water back and forth. (Image and video credit: Practical Engineering)
Pumping Waste
Sewage systems rely on gravity to remove waste from our homes and carry it toward treatment plants. But that constant downward slope can’t always be maintained. Sometimes we have to bring the sewage back up to the surface to process it. For that, modern systems rely on pumps and other equipment to move the challenging slurry of liquid and solid materials. In this video, Grady from Practical Engineering breaks down the physics and engineering of sewage pumping. (Image and video credit: Practical Engineering)
The Best of FYFD 2021
A year ago I observed what a strange year 2020 had been, and in many ways, I could say the same of 2021. Before the pandemic, I spent quite a lot of time traveling. In 2021, the only nights I slept outside my own bed came on a long weekend up to the mountains with my family. But 2021 also saw a bit of a return to normalcy – I was giving keynote addresses and workshops again, albeit virtually. What will 2022 hold? Who knows?!
As per tradition, here are the top FYFD posts of 2021:
- A superior mirage leaves a ship floating in mid-air
- Drone videos of sheep herding are mesmerizing
- Permeable pavement allows water to drain
- The slow and dreamy fluid landscape of “Le Temps et l’Espace”
- What do you do when you’re an insect researcher with a high-speed camera?
- Satellite images… or paint?
- The intricate lacework of the Venus’s flower basket sea sponge
- Building a Bluetooth speaker with ferrofluid music visualization
- Finding the acoustics of Stonehenge
- Making butter by traditional French methods
It’s an eclectic mix of topics this year: bizarre phenomena, stunning art, archaeological exploration, and a touch of biophysics!
If you enjoy FYFD, please remember that it’s primarily reader-supported. You can help support the site by becoming a patron, making a one-time donation, buying some merch, or simply by sharing on social media. And if you find yourself struggling to remember to check the website, remember you can get FYFD in your inbox every two weeks with our newsletter. Happy New Year!
(Image credits: mirage – D. Morris, sheep – L. Patel, pavement – Practical Engineering, Le Temps – T. Blanchard, insects – Ant Lab, Satellike – R. De Giuli, sea sponge – G. Falcucci et al., speaker – DAKD Jung, Stonehenge – T. Cox et al., butter – Art Insider)
Dune Invasion
Migrating sand dunes can encounter obstacles both natural and manmade as they move. Dunes — both above ground and under water — have been known to bury roads, pipelines, and even buildings. A recent experimental study looks at which obstacles a dune will cross and which will trap it in place. Their set-up consists of a narrow channel built in a ring, essentially a racetrack for dunes. Flow is driven by a series of paddles that rotate opposite the tank’s rotation.
The team studied obstacles of different shapes and sizes relative to their dunes, and they found that dunes were generally able to cross obstacles that were smaller than the dune. Obstacles larger than the dune would trap it in place, and, for obstacles close to the same size as the dune, round obstacles were easier to cross whereas sharp-angled ones tended to trap the dune.
The idealized nature of their experiment means that their results aren’t immediately applicable to the complex dunes of the outside world, but the study will be an important touchstone for those predicting dune behavior through numerical simulation. Studies like those require experimental cases to validate their baseline simulations. (Image credit: top – J. Bezanger, figure – K. Bacik et al.; research credit: K. Bacik et al.; via APS Physics)
Pressure At The Dam
Hydrostatic pressure in a fluid is based on the fluid’s depth. You’ll rarely see a more dramatic example of that power than with a water release from a dam. Here we see the outlet of the Verbund Hydro Power dam in Austria. With 190 meters of water behind the dam, the outlet jet is massive. It moves 20,000 liters of water per second at a speed of 50 meters per second. Imagine what it would be like to stand next to that! (Image and video credit: Discovery UK; submitted by Olwyn B.)
