Tag: civil engineering

Pipe Flow and Pressure
Whether you’re a homeowner or an engineer, at some point you’ll have to deal with pipe flow and the challenges inherent to getting water from Point A to Point B. This Practical Engineering video provides a great basic overview of pipe flow and pressure loss, whether you’re looking for an introduction to the topic or a little refresher. It’s also got some small-scale demos in an actual system to help you build intuition for what changing pipe length, diameter, and fittings does to the flow. (Video and image credit: Practical Engineering)
June 29, 2021
Where Does Stormwater Go?
Stormwater management is one of the biggest municipal challenges towns and cities face. Urban surfaces are largely impermeable, preventing rainwater from soaking into the ground. Instead roads, ditches, and channels collect water and, typically, divert it as quickly as possible into natural waterways.
In contrast, wild landscapes tend to slow water run-off, filtering it into the water table, soaking it up with vegetation, and distributing it across a larger area. Recently, cities have started using low-impact development strategies, like rooftop gardens and rainwater collection, to mimic natural landscapes in urban ones. (Image and video credit: Practical Engineering)
June 10, 2021
Protecting From Storm Surge
The most dangerous and destructive part of a tropical cyclone isn’t the wind or rain; it’s the storm surge of water moving inland. This landward shift of ocean takes place because of a cyclone’s strong winds, which drive the water via shear. The depth storm surges reach depends on the wind speed and direction, shape of the shoreline, and many other factors, making exact predictions difficult.
Fortunately, engineers can — with enough foresight and investment — build structures and networks to help protect developed land from storm surge flooding. (Image and video credit: Practical Engineering)
April 12, 2021
Coastal Erosion
The same dynamic forces that make coastlines fascinating create perennial headaches for engineers trying to maintain coastlines against erosion. This Practical Engineering video discusses some of the challenges of coastal erosion and how engineers counter them.
In a completely undeveloped coastline, waves and storms erode the shoreline while rivers and currents replenish sand through sedimentation. Manmade structures tend to strengthen erosion processes while disrupting the sedimentation that would normally counter it. Beach nourishment — where sand gets dredged up and deposited on a beach — is an engineered attempt to replace natural sedimentation.
Dunes, mangrove forests, and wetlands are all nature’s way of protecting and maintaining coastlines. We engineers are still learning how to both utilize and protect shorelines. (Image and video credit: Practical Engineering)
March 2, 2021
Permeable Pavement
Controlling storm water is a major challenge in urban environments, where many surfaces are impermeable. In a city, rain cannot simply soak into the ground and filter into the water table. One potential solution is permeable pavement, which uses the same ingredients as its common counterpart minus the sand that usually packs into gaps between the gravel. Without the sand, the final pavement allows water to soak through, as seen above. In practice, the water sinks into a porous reservoir beneath the pavement that helps store and regulate the water’s discharge into the soil.
Unfortunately, this solution has its limitations. Permeable pavement is not as strong as the regular variety, so it doesn’t work for highly trafficked areas like roadways. It’s also not well-suited to colder areas, where freezing and thawing may disrupt its operation. But it is another tool in engineers’ toolboxes when it comes to keeping urban environments in harmony with nature’s needs. (Image and video credit: Practical Engineering)
February 5, 2021
Preventing Flooding
The Dutch have been exceptional water engineers for centuries, a necessity in a country where more than a quarter of its territory lies below sea level. After a devastating flood in the early 1950s, the country embarked on a decades’ long endeavor to build the massive Delta Works that now protect a large portion of the population from oceanic storm surges that would otherwise flood the countryside.
As part of their efforts to instill resiliency both along the coast and upstream, the Netherlands has shifted dykes, created floodplain habitats, and built water storage into new buildings. With communities around the world at greater flood risk than ever as our climate changes, the Netherlands serves as a shining example of what’s possible with proper planning and investment. (Video and image credit: TED-Ed)
September 30, 2020
How Canal Locks Work
For thousands of years, boats have been a critical component of trade, efficiently enabling transport of goods over large distances. But water’s self-leveling creates challenges when moving up and downstream through rivers and canals. To get around this, engineers use locks, which act as a sort of gravity-driven elevator to lift and lower boats to the appropriate water level. In this video from Practical Engineering, we learn about the basic physics behind locks as well as some of the methods engineers use to limit water loss through the lock. (Image and video credit: Practical Engineering)
September 14, 2020
The Engineering of Culverts
Manmade infrastructure often interferes with natural waterways, which is one reason civil engineers turn to culverts, those pipes and concrete tunnels you often see beneath roadways. As simple as they may seem, there’s a lot of engineering that has to go into these artificial waterways to keep flows from backing up and flooding roads. In this video from Practical Engineering, you’ll learn about some of those factors and see through demos just how they impact the flow. (Image and video credit: Practical Engineering)
July 31, 2020
Michigan Dam Failure
Last week Michigan’s Edenville Dam failed, triggering catastrophic flooding. While the exact causes of dam’s failure are not yet clear, this video of the collapse provides some interesting hints.
As the video begins, we see water that’s already trickled down the slope, potentially a sign that the top of the dam has already degraded. Then a noticeable bulge forms near the bottom of the earthwork slope, followed quickly by a landslide. Water doesn’t pour out immediately, though. That delay suggests that only part of the dam’s thickest section failed in the landslide. During the delay, the remaining interior of the dam is failing from the sudden lack of support. Then, the floodwaters come pouring out.
From the sequence of events, it seems likely that the dam was suffering from soil liquefaction prior to the collapse. With high water levels behind the dam, pressure can drive water into the soil beneath the dam, reducing its strength. You can see this effect in action in this video and this one. For more on the Edenville dam specifically, check out the great analysis over at AGU from Dave Petley (1, 2).
Sadly, failures like these are quite avoidable, provided dams are properly maintained. Climate change is drastically altering precipitation patterns across the world, and without updating and reworking our infrastructure to account for that, we’ll see more failures like this in the future. (Video and image credit: L. Coleman/MLive; via Earther; see also D. Petley 1, 2)
May 27, 2020
Holding Pipes in Place
Newton’s 3rd law states that any action has an equal and opposite reaction. Often engineers use this to our advantage; the thrust from expelling propellants is what lifts our rockets to space. But sometimes those reactions are undesirable, as illustrated in this Practical Engineering video with underground pipes.
Anytime flow through the pipe is forced to change direction, the flow causes an equal and opposite force on the joint. Just as with rockets, engineers refer to this reaction force as thrust. And if the thrust goes unaccounted for, it will force pipe joints apart. Civil engineers use several methods to fix pipelines against these forces, including concrete blocks that distribute the force to the surrounding soil and flange fittings that resist pipe movement. (Video and image credit: Practical Engineering)
May 4, 2020