What is a Weir?

A weir is a small dam built across a river to control the upstream water level. Weirs have been used for ages to control the flow of water in streams, rivers, and other water bodies. Unlike large dams which create reservoirs, the goal of building a weir across a river isn’t to create storage, but only to gain some control over the water level. Over time, the term weir has taken on a more general definition in engineering to apply to any hydraulic control structure that allows water to flow over its top, often called its crest. In fact, the spillways of many large dams use weirs as control structures. So how do they work?
Watch this video and the entire Practical Engineering catalog ad-free on Nebula: go.nebula.tv/practical-engineering
-Patreon: patreon.com/PracticalEngineering
-Website: practical.engineering
Writing/Editing/Production: Grady Hillhouse
Tonic and Energy by Elexive is licensed under a Creative Commons Attribution License
Source: kzbin.info/www/bejne/i2fJc4Oaqp2qb7c
This video is sponsored by Skillshare.

[@RealEngineering]

Found this really interesting. The weir in Galway, my hometown, creates a pretty unique cityscape. I have always been fascinated by it, but never really put much thought into it why it existed.

[@garethronaldo8692]

oh i love you both

[@wille4w]

Depending on the wildlife, weirs can be hazardous. Usually to wolves in the moonlight.

[@damearstill6184]

Both of these channels are my favorites. Sucks that this one posts once in a millenia but still good😀

[@redmondokelly2464]

So that's why they called it the salmon weir bridge. I always wondered where it got it's name from but never put 2 and 2 together. Thank you!

[@aidanthornbury]

Glad you're here Brian because I have a question that could interest both you and Grady. Just before introducing the labyrinth weir, Grady introduced the question of "how do you control the flow rate without the ability to increase structure length' (excuse the paraphrase), and my initial thought was "make it a V." To clarify, in my mind, I meant vertically introduce a slope across the length of weir where the lowest point would be at the center of the structure, and the highest points on the banks, not the types of "v's" mentioned in the video. I ask both of you: any validity to that idea? As I sit and think on it more, I realize that it would most likely cause more water level fluctuation than a standard flat weir, but maybe there might be some form of benefit to that design. I don't know. Also, any chance you're doing a meet-and-greet any time soon, Brian? I'm in the UK for the semester (planning on seeing family in Ireland), and It'd be awesome to get to meet and chat a bit. Looking forward to new videos from you both! Thanks for the read!

[@JohnGuastavino1]

Me the next time I see a weir: "It's actually called a weir."

[@lassemanninen4750]

Be prepare to have ur ass whipd after that.😘

[@ferociousmaliciousghost]

How weird.

[@tiddiesprinkles]

Dam really?

[@checkcheck1579]

theres an ogee underneath it too

[@RetepAdam]

Weir flex, but okay.

[@narcissistectomy5134]

So it’s grammatically correct to say that all rivers get “weird” after a weir is built.

[@foxopossum]

🤣🤣🤣

[@moihawk666]

whats a weird river?

[@Thestuffnope]

@@moihawk666 its a play on words. Put the letter d on the end of weir and you get the word weird.

[@Thestuffnope]

@@moihawk666 its a play on words. Put the letter d on the end of weir and you get the word weird.

[@brianmeese1641]

“Weired”

[@marksanders768]

Weirs have also been used, historically, for fishing. Some of the oldest weirs were built in a triangular fashion almost exactly as shown towards the end of this video, made of rocks placed across shallow rivers. This allowed water to flow over while trapping fish, behind, which could then easily be caught. There are some pretty obvious downsides to this approach - namely that it almost completely stops the ability of fish to move along the river's course - but old, historical examples can still be found, at least in pieces, in small rivers and streams.

[@frhorizons]

At the Etowah Indian Mounds, they still have such a structure in the river, and the engineering behind it is genius. They would essentially bottleneck fish into "breaks" in the weir large enough to fit a basket into, then scoop one up and it would be filled with fish

[@konnorandrews172]

Still commonly used in the southeast in smaller rivers specifically for eel weirs and they actually have (very few) licensed weirs because its been a generational method of eel fishing for some of those families

[@allenlutins]

Not only historically, but prehistorically as well (going back thousands of years).

[@blipco5]

I'm one who loves viewing dams and structures built to control waterways for our benefit. If I see a sign along the road that says "dam", I immediately turn off and investigate. This information will help me further bore my friends. Thank you for that.

[@KaiIngebrigtsen]

damn.

[@spacedoge3508]

Damn

[@Devo57]

blipco5 I like to go on google earth and follow random rivers to see what dams are along it.

[@ninnin8858]

Oh dam

[@amoghavarshamurthy]

You are a person after my heart 😀

[@flappy7373]

If a pier is an artificial outcropping over water for people, then it makes sense that a weir is an artificial outcropping over water for water!

[@desmondyap5391]

mind-blown

[@3longatedMuskr4t]

Kyle Mouttet Cambridge called bruh, they wanna know if you prefer on campus or off campus living.

[@ursusss]

Ba-dumn-tssss

[@bengully5076]

Deep

[@aurelia8028]

how _wierd_ ...

[@cwd1312]

Your videos should be shown in all schools to inspire young minds. I am a 69 year old retiree and I'm a perfect example of a why videos like yours are important! When I was in school I hated math and I was a mediocre student overall. I always say if that math could have been presented in a way that was interesting to me then I would have excelled in my studies. I did ok during my career, although when I look back at my life I would have enjoyed being a mechanical engineer because I have a natural inclination for it. If I had only known what was possible when I was a teenager in high school I would have taken a very different path!

[@mechez774]

Engineering as presented to young people is indeed extremely interesting. Many of these bright young minds become disillusioned however when they finally secure a job with an engineering firm and spend their days slogging through spreadsheets

[@keenanevans7888]

Nice.

[@petersipp5247]

Math in high school was so "abstract" I feel like you about it. Could not see it's purpose.

[@traybern]

I suppose someone as DUMB as you questioned why they taught you to READ too, huh?

[@traybern]

DAM!!!!

[@bruner]

My small town just replaced a dam and now I know why the new spillway is such a strange shape.. It's a labyrinth weir! Thank you 🙂

[@SkoobySkeptic]

I had no interest in weirs but clicked on this all the same. Turns out I found your description and examples very interesting. Bravo sir.

[@bobleclair5665]

SkoobySkeptic Indians used weirs on beaches to catch fish,,,kinda like a Corel,,the tide would come up along with fish,fish would swim into the corral,,then when the tide went out,the fish where caught,,there’s one in Rye NH

[@joeysplats3209]

What? No inane insults? Bravo, sir!

[@mcsyneuroscience6488]

What does 'bravo' means sir?

[@MO-ch6ni]

The amazing photo got me XD

[@vn-dc3hv]

3:10 "So how we can flatten this curve?" Flattening curves before it was cool.

[@DanielDaniel-xz2yp]

ikr, everyone a copycat

[@TheMatin1]

Remove the weir.

[@davido3026]

Curves flatten after ladies age!!!!

[@Idahoguy10157]

Weirs, especially old weirs, are a danger to Rafters and kayakers. We try hard to know where they are

[@derriusbranch8620]

Hi

[@derriusbranch8620]

Hi Go good things and Sciences. And go good things. And go good films. And go Kodak's and go good picture groups. And go good things.

[@HaveANiceDayLol.]

"Robert it do go down!"

[@jacobackley502]

"Death dams." They look so harmless but suck you down and drown you

[@wakatobikreatif8788]

@Schlomo Baconberg pp0

[@ameyring]

There are too many comments to search through to see if it's mentioned, but water treatment plants also have weirs for sedimentation basins. As fair as I've seen, they are fixed and set to keep the water basin at the same height all year.

[@Safar_Galimzyanov]

Thanks

[@mechez774]

Also wastewater uses weirs , basically for the same typemof sedimentation process

[@seabastard3747]

KZbin: Ever wondered about Weirs Me: Nope "click" And yet i watched it all, great vid.

[@michaelsmith9714]

Seabastard same here.

[@farticlesofconflatulation]

Me: ever wondered when to use an apostrophe?

[@HKRazieL]

@@farticlesofconflatulation Me: Nope "click"

[@helldronez]

lmaoo me too XD

[@TedOfNod]

That apostrophe doesn’t belong there. I swear on yo mama’s

[@RinoaL]

6:06 Piano Key Weirs look like something The Empire would build. it has a very "deathstar" aesthetic.

[@EQMVB]

Totally agree with you!

[@nicholasmcgregor6974]

British Empire or Galactic Empire?

[@Johnny.Picklez]

@@nicholasmcgregor6974 galactic empire

[@krel7160]

Or like Hyperion, from borderlands, for that matter.

[@cpmenninga]

I came for the piano key weirs and wasn’t disappointed.

[@jsand8301]

You should definitely do a video on the dangers of these structures. I learned early in life (age 14) of the danger of these structures when a neighborhood kid died falling off of one while trying to walk across.

[@PracticalEngineeringChannel]

I have. Search for the “most dangerous dams”

[@Gsoda35]

we might need something that blocks passage over a weir.

[@asluckdespairs]

​@@Gsoda35 already have it. Its called common sense.

[@Juusori]

@@asluckdespairs That works just fine because young kids always use common sense, right?

[@jbatrust1472]

We put together a video with our local Fire & Rescue Service using a 'water safety flume' specifically designed to show the dangers of weirs and other structures in rivers - you can check it out here: kzbin.info/www/bejne/i4C1dpZ8fbV4n7M

[@SwirlingDragonMist]

‘When a tree falls in the river, does it make a weir?” lol

[@carlwilliams6977]

If you're a kayaker, it makes a "strainer"! 😲

[@petermgruhn]

Damn.

[@69CamaroSS]

Possibly….if it falls ACROSS a river 🤔

[@austinlane5533]

Honestly, that's a "weird" question..

[@kabel7638]

I have a creek in my back yard with trees fallen over into it and i can say yes it does act similarly however it does cause some issues when they rot and move with the water

[@ArztvomDienst]

Everything is interesting, if you go into it deeply enough. ~ Feynman

[@miapdx503]

George Washington Carver knew something about that.🙄

[@mosinnagant3162]

We are lucky to live in an age in which we are still making discoveries. Richard Feynmann

[@run4eva]

Like a Virgina ~me

[@feuby8480]

It's all fun and games until you find a balrog.

[@PennyDreadful1]

He was also rather fond of going into female genitalia in some depth. Sometimes his friends wife's genitalia. He was just curious like that.

[@bradleysmith9431]

Just proves that even the simplest looking objects, turn out to be complex after investigating.

[@duerf5826]

Most people have no idea how much of their surroundings are engineered, but at the same time, look quite natural. For example, some trees on the side of the road probably don't mean much to most people but they may be a part of a complex hydraulic system.

[@hermand]

As soon as I heard "Co-Efficient" I realised into something much bigger than I thought!

[@sandyvillamar1652]

Exact point of the cybertruck.

[@kiringperson8873]

Hello

[@kiringperson8873]

Contact no

[@brianthesnail3815]

We have a weir on the river in our town (in the UK) which had a large positive economic impact. It was built to increase water level for what was an inland port back in the 19th century. It helped as bigger boats could come up the river from the sea and it also allowed a canal to join the river without very large locks. The only downside was the river had to be continuously dredged as sediment got stuck behind the weir. Sadly our town no longer has the port which hit it very hard economically, but the river has reverted to a wild river, shallow and full of fish.

[@vatoguanajuato3892]

I’m gonna build one. This is what I needed to know. I was gonna just do a normal wall but now it’s gonna be like that triangle shape and help with the flow to not cause damage

[@Barnaclebeard]

In Canada, among paddlers, weirs are also called "drowning machines." If you go over a weir, the fluid dynamics will often pin you to the floor of the river and won't let you up for a very long time.

[@Timsturbs]

that's awful should be called "drowning structures"

[@Barnaclebeard]

@@Timsturbs, please enjoy this high-quality Canadiana. kzbin.info/www/bejne/f4K3eYmmesqId68

[@SulfuricDonut]

Doesn't necessarily pin you to the floor, but rather gets you stuck in a re-circulation zone where every time you float back to the surface, the negative velocities pull you back to the weir and launch you under again. I made a Lego-man demo for my hydraulics students at university: instagram.com/p/Be1RskCHphySYvOdVjIZLipOUQ9IBwEIkIyxAI0/

[@dantheman3022]

@@SulfuricDonut cool Gotta try my new body board out its like an endless wave then hehehee

[@hededcdn]

Reminds me of the Elbow in Calgary.

[@huskykhtam]

youtube randomly recommends this video and I find it interesting.

[@AurumFaber]

KZbin is good at what it does.

[@rodneyradoll2959]

Yup

[@markuskuhn4418]

Same

[@greatkingkay7954]

Same here. When I was young I have a book on dams , orifice and weir. But I never bother reading it.

[@le-jaunemorgan6563]

That's because KZbin is studying you. Have you ever seen a survey where they ask you if you liked a certain video? That and they recommend based on what content you have watched and which websites you visit.

[@alexkathurima4508]

I was revising for my fluid mechanics paper and came through this and I genuine appreciate engineering

[@robertharvey6725]

Great summary, much enjoyed. Another long-used method of improving flow was to place the weir at a slant or curve in the channel. The most beautiful example is the weir below the Pulteney Bridge on the River Avon in Bath, England.

[@nicholasbrownlee4209]

You're the real ogee of engineering channels on KZbin. You provide valuable inflow on many different topics and although this video is a little bit weir, I still find it quite interesting.

[@diamondflaw]

"the real ogee" Let's hear it for the attractive double "S" shape!

[@nicholasbrownlee4209]

@@Lucidbkeo That was another pun. He uses the term "ogee" as a technical designation in this video.

[@nicholasbrownlee4209]

@@Lucidbkeo Many thanks. I take my job very seriously!

[@marisam9803]

"Youre the real ogee" I saw what you did there 👍

[@pw9683]

@@Lucidbkeo "head" niiice

[@PlasmaHH]

You forgot those where the height is not the same at every spot, often combined with triangle or rectangular shapes. The higher the water gets, the more length it has to discharge.

[@alaric_]

My first thought was this. Pyramid shapes allow less water to pass when low water level but should increase the flow when water level get higher. Well, in laymans mind at least...

[@ZacDonald]

My first thought was having some sort of stair step design, where the rare high waters/flooding scenario would basically bypass a lower weir by design.

[@JamesSeedorf]

These would lead to a higher water level in all cases, so it doesn't really do anything to help solve the problem in the video. They do potentially allow for reduced wear and tear on the dry side but that is about it

[@andrewnotRFAC]

V notch weirs are the most common. The higher the water level, the more flow is allowed to pass at it climbs up the "V"

[@PKMartin]

@@andrewnotRFAC I was hoping for some discussion of V notch weirs- a friend who worked for the water board bored us all senseless on a hike to a reservoir pointing out V notches, "the only type of weir with consistent cross section geometry for any water level"

[@micsierra806]

4:19 Props to the Valve - Half Life 2 developers. I didn't realize that after I beat the hunter helicopter in Water Hazard and opened the gates I jumped over a weir. Solid.

[@MisterBones2910]

From a game design perspective that was a "sawtooth" as well. Half Life and especially Half Life 2 make liberal use of them.

[@garfixit]

You are making this interesting for people that might not have thought of how much work it takes to create a sustaining infrastructure. Thank you for sharing your talent

[@gordonlawrence4749]

In the UK weirs were also installed to help clean up rivers. IE to introduce oxygen and remove carbon dioxide from the water in order for aerobic bacteria to get rid of (metabolise) certain classes of pollutants.

[@dcviper985]

In my hometown of Columbus, OH, we actually removed a series of low head dams and weirs from the Olentangy River in order to improve river health. It also lowered the river level, and they build a really pretty park smack in the middle of the city center.

[@gordonlawrence4749]

@@dcviper985 It depends on the specific issues.

[@Godshole]

I once lived by a weir on the river Aire. It always surprised me that the smell around it was a'kin to stale washing machine water. You could define hints of laundry detergent along with a few hundred years of washing wool fleeces and a hint of iron.

[@gordonlawrence4749]

@@Godshole It would have been worse without as it would have got stagnant like the Thames was and several other rivers.

[@Godshole]

@@gordonlawrence4749 Thinking about it a bit more, the weir was to provide head for a mill related to the Saltaire area. Named Hirst Mill and Hirst Weir, there is a link to a picture i found here. www.geograph.org.uk/photo/1340593

[@RossOzarka]

Weir, ogee, nappe-- so many great scrabble words!

[@JohnBorgen]

In old-world window manufacture of double-hung windows they use something called a "Roman Ogee" to stop the top window from coming all the way down. Interestingly, they look remarkably similar in shape to the ogee featured in this video. Makes me believe there's a correlation.

[@RossOzarka]

@@JohnBorgen looks like the word Ogee broadly means Sigmoid curve, which must be why its found in both design and engineering

[@pihermoso11]

@Mike Spencer i think we'd be more proficient in the english language if we all study latin.. even most of the elements in the periodic table have a latin name and meaning of origin

[@hugebartlett1884]

@@pihermoso11 My knowledge and understanding of the English language was greatly enhanced by studying and learning Latin.

[@theapexsurvivor9538]

@aboctok don't worry, it's just Orkish slowly taking over. So long as you say that you need more dakka, you'll always be alright (an if ya needz ta hide, just pain yaself purple).

[@BAgodmode]

I’m from Texas and growing up I remember swimming in a natural pool of some sort near Georgetown or Austin that had a weir. Also in parts of Arkansas as well, there was a spring that discharged super cold water that they built a weir. Best swimming pools when it’s 100+ out.

[@1945d18]

Weirs are also used for measuring flow rate as well as controlling water level as the equation allows the flow rate to be calculated for various heights above the weir crest which can be monitored by various methods such as electronic sensors that take data and convert the depth to flow rates. As an engineer have installed many weirs in my time. Very useful devices for sure

[@tomschmidt381]

As a retired EE, enjoy your engineering videos. Here in New England many flow control structures use a low tech flow control method, flash boards. Wooden board are mounted at the top of the structure to increase static water level. In a high flow situation the boards break away. Crude but effective for small structures. To your other point New England is littered with small dams used for water power in the 18th and 19th century. Many have been breached to improve aquatic conditions and fish migration. We had a lengthy discussion about breaching a couple in our town several years ago. Ultimately decided not to remove them as the impounded water is integral part of town. The other concern is release of contaminants held in sediment behind the dam, luckily in or case that proved not to be a severe problem. Love your enthusiasm for engineering hope you have a long and successful career.

[@fal3881]

Mom : Son look a mini water fall Son : Actually, its called Wier

[@ferociousmaliciousghost]

Dad: How *WIERd!*

[@HaveANiceDayLol.]

Random homeless guy nearby: *wheeze*

[@JulieWallis1963]

Actually it’s called a *weir*

[@Pidalin]

here in Czechia, word for weir is more common than word for water fall or dam, I guess it's because there are weird everywhere and most of Czechs are canoing or rafting at least once in few years

[@alalalala57]

@@Pidalin I agree. That's weird.

[@P-Bass_Pete]

I used to work in a Sewage Treatment plant, many of the tanks used to process the water contained weirs. For example, in a round Thickener tank, waste water would be pumped in from the top center of the round pool shaped tank. The heavier waste sludge would sink to the bottom, which instead of being flat like a pool was cone shaped. It was pumped off into a what's called a digester tank to be further processed. The grease would float to the top where a rotating skimmer arm would push it into a box to be collected and pumped away. The now clearer, cleaner water would flow up and over the weirs at the outside circumference of the tank to move on to the next process. We used a formula to calculate the amount of water flowing out over the weirs per hour and the pumping rates of the various pumps letting water into and out of the tanks.

[@pboston6RR]

Both your presentation and content organization are outstanding! Doing it without a live audience is a daunting task which you have mastered. Thank you!

[@seanwalter9383]

During the video you say, "Flatten the curve." I can't help but think that's why you just now showed up when I've been watching corona virus videos. The algorithm listens!

[@abhiinair]

I thought the same!! Haha.

[@seemslegit1316]

Google is always listening 👁

[@SnootchieBootchies27]

Way to go, you probably just demonetized the poor guy.

[@seanwalter9383]

@@SnootchieBootchies27 considering I made this comment 3 weeks ago and all of the responses are from today, I think he's doing alright

[@seanwalter9383]

@@threadie technically now yesterday although I made that comment after midnight which is technically today but I referred to yesterday as today when it was really yesterday. You understand don't you?

[@MichaelOnines]

We can use a fractal wier to fit an infinite length of wier into a finite width of river. Problem solved! (Consider a spherical cow in a vacuum...)

[@davidgrover5996]

Michael Onines, The Spherical Cow the holy grail of cattle breading endless steaks.

[@davidaIano]

yea but then you have a problem, fractal water.

[@MichaelOnines]

@@davidaIano, fresh water crises officially ended; you are brilliant!

[@MichaelOnines]

@@davidgrover5996, the spherical salisbury?

[@davidgrover5996]

Michael Onines, sounds delicious.

[@blchamblisscscp8476]

Thank you for this. As a tourist to Bath, UK several times, I've always wondered about the weir on the downriver side of Pultney Bridge on River Avon. It's made of several severely arched weirs stacked together.

[@georgebond7777]

There are also V shaped weirs, we use these in drainage detention systems to control the outflow downstream in the event of higher ARI storms. You do a great job presenting our profession.

[@justicewarrior9187]

FREAKING FINALLY KZbin!!! A super interesting video were I actually learned something I never heard before!

[@justicewarrior9187]

@Nunovia Gottdamnedbizzness Wut m8?

[@oldgreggscreamybaileys6618]

Tom Scott? I’m sure he can tell you some things you might not know.

[@njones420]

@@oldgreggscreamybaileys6618 haha, just came from a Tom Scott vid....

[@oldgreggscreamybaileys6618]

N Jones haha the circle of knowledge in full effect

[@bantot1296]

KZbin: _hey you goin' to sleep?_ Me: yes, now shut up KZbin: *_What is Weirs_* Me: **wakes up**

[@wafiywahidi3317]

*so the river just got "weir'd"?*

[@macroplexx]

Es, hasta el momento, el mejor ingeniero civil en el que puedo confiar por las explicaciones claras y objetivas en la practica. Muchas gracias

[@icedlatt3]

Grady speaks so well and explains so concisely and with brevity. He's able to find the perfect balance and give just the right amount of info without overwhelming the viewers, and make learning so engaging at the same time. Just wow, gj dude.

[@Kyntteri]

Dam if you do, dam if you don't. It's weir, I know.

[@kriskringus2191]

Kyntteri we live in a society

[@MikhaelAhava]

Ok.

[@ROGER2095]

Hi-Yo!

[@seeds8631]

Kyntteri you can leave now

[@Kyntteri]

​@@seeds8631 I'll get me coat

[@randomstuffbychris]

I very much appreciate the effort you put into these videos, the scale models make it much easier to understand all this information

[@distantsignal]

HI Grady. I love your videos! I'd never even heard the term "weir" before seeing this. Fascinating info and doubly fun learning something you didn't even know you were interested in.

[@chriswixtrom6514]

That's what keeps happening to me. Never heard of something but if it's on Practical Engineering, I know it will keep my attention! I got the book, too!

[@beeman2075]

The extent of my knowledge of a weir until now was that it's a kind of dam, with double question marks at the end of that line. This was really interesting to watch.

[@mylord7268]

The photo of the Hoover Dam at 4:09 shows a high water level overflowing into the spillway. It must have been taken more than 20 years ago. The water level is so low now that there is about 100 to 150 feet of the intake towers are exposed.

[@ArtumTsumia]

Now you've got me wondering what the flow into the dam is like. I visited recently and the water is significantly lower than the towers or overflow weirs, but there's other places that the water flows out during 'normal' usage, so there would probably need to be significant watershed upstream or perhaps oncoming drought where they want to store that much.

[@rupe53]

@MrCloudseeker ... the bypass tubes were used during the original construction so they had a dry area to build the dam. The original tubes have not been used since then. Most likely there are more tubes within the dam itself but I have never seen any reference to them. Perhaps they are there to flush silt from the bottom? Who knows?

[@dsc623]

Awesome video! I’ve heard the term weir so many times at work and have a much better understanding now. Keep up the good work!

[@eddieandrews3335]

That was really interesting and done in a professional way. I honestly thought this dude was a professor or civil engineer. Thumbs way up for nailing it

[@Trenz0]

He is a professional Civil Engineer (as in he has a P.E.) so... Undoubtedly the latter, and education-wise essentially the former

[@kebakent]

I feel like beaver dams would be interesting to analyse, in regard to these engineering topics.

[@Ididathing]

Well, i'll be "damed".

[@terryboyer1342]

You're "weired".

[@cheapalopod8563]

Wat'er you saying?

[@kv501]

It’d be “dammed.”

[@PrograError]

this tread is in tension

[@SergeMTL]

makes me turn on the "waterworks"

[@kevinstanley3581]

Great and informative video. What wasn't mentioned was that some weirs are constructed solely for flow measurement such as residual flows, compensation water etc. Well ventilated nappe always comes to mind.

[@SuperTrunkspace]

Watching the fluid flow reminded me a lot of studying casting in college. A lot of the structures used in the gating system of a casting could probably be either derived from or applied to what you're talking about! Flow control is very important in casting as well. Very interesting to see how different branches of science overlap :)

[@visualartsbyjr2464]

The dam by my place very recently received upgrades, one of which was a passive folded weir for overflow.... it’s nice to know technical terms. Thank you for the videos!

[@frequencymanipulator]

10/10 for having acoustic treatment in your room.

[@Ravenwish1990]

I used to live in a city that had a variable weir with a rubber membrane, managed with what I can only assume was air pressure. Always found it super interesting.

[@FrozenBusChannel]

Same here! It's like long flexible tube, letting water flow over the top

[@vedvids9319]

KZbin algorithm heard 'flatten the curve ' thought this is relevant in present times and recommended it ,,,, Very subtle

[@leonardsalt]

Tought the same as I heard it! Amazing how both noticed it!

[@Raison_d-etre]

You really think delivering videos that people will click on takes this much work? How about the fact that you clicked on his previous videos?

[@vedvids9319]

@@Raison_d-etre the comment literally meant it's not much work , and I just explained how I came across this video .

[@Raison_d-etre]

@@vedvids9319 Yeah okay, if you think transcribing every video to look for current phrases is an easier explanation than the fact that you've clicked on this or similar channel before.

[@vedvids9319]

@@Raison_d-etre Im defeated . Pls enjoy the day!

[@douglaslarson532]

I have known of weirs for many decades. I first learned about them when I was a teenager and observed weirs in irrigation canals which were used to divert water to a side channel or to an extraction pipe. I found these simple structures fascinating. Thanks for this video.

[@harlequinharlikwin]

Brady is a good compere. He has the charisma ( with the voice and fluency of the subject) to make people stick around to a serious subject.

[@travisjantzer]

That Piano Key Weir looks super cool. I think I'm gonna make one as a water fountain.

[@Dean0ne]

this is probably the first video of this channel i came across but the production quality is so good i might stick around. i like the way he talks, it's easy to follow and clear to understand. but i had to stop the video at around 3:11 because that's where i realized: the white background is actually a textured wall. that means even tho the graphic is made digitally, the background wasn't left completely white. now this indicates to me, that they decided that a completely blank white background would be maybe too boring or too bright on the eyes, but whichever reason, small details like that always amaze me on youtube. because it just makes me appreciate the effort that goes into some videos even more! so keep up the great quality!

[@johne.osmaniii7217]

Claudio Viola, true, but I was gonna subscribe, to the interesting parts anyway, ...lmbo!

[@JonnyD3ath]

There is an insane amount of work that goes into seemingly simple youtube videos, i learn more and more all the time like you and it makes me appreciate the effort these guys goto

[@Sandbull22]

Came across a piano key weir without knowing what it was and thought it was absolutely fascinating. The water wasn't flowing over, so we were able to climb to the bottom. The vertical walls were probably close to 20 feet high! Cool to finally know what it was

[@Sandbull22]

@The Insufferable Tool on a road called 'tail of the dragon'. It's a popular driving road in TN and NC and the weir is on the Maryville TN side. It is not in the super curvy part of the road. I think the road is US 129 but not 100% on that

[@CrimsonAkato]

I haven't seen any fancy wier , just the Normal ones that are basically a slope I live close to rivers and there was a weir like that like very far into the forest , the area felt private closed from all the tall trees and the weir looked like a nice couch I just decided to sit down on a hot summer day and enjoy all the water slowly following over on top of me , it was great unfortunately that forest got ruined cuz someone got the land and built like a huge caffee place , and it's very annoying cuz I can't play in my river now with there always being people who can easily look down . how annoying I'll miss my private river spot was fun while it lasted

[@bobpatterson9026]

I wanted to add another use for a weir. Years ago I worked for a municipality and we wanted to check an output of a local spring. We installed a weir so we could measure the output

[@jsnthurst1]

Grady, just wanted to say that you produce incredibly good educational videos!

[@danjajeff1404]

Interesting. I used to weld and fabricate for a company called Rodney Hunt, who was bought out by Fontain gates and valves. Anyways we used to make those huge gates and valves so big you could literally drive a small car through them. Also did some work in the Hydraulics Dept which was cool to build those units that lift and turn those gates and valves. EXTREMELY high pressure passing through those units. Cool video.

[@_JayRamsey_]

Rodney Hunt! I was just working at a hydro site in Rhode Island with gates made by them. Didn't expect to see the name on YT.

[@danjajeff1404]

@@_JayRamsey_ yeah it's a great company and pays well too. Great product made from the scrap metal to finished product in the USA. I started off in the foundry and worked my way up. I was able to see the entire process from start to finish. Cool stuff if that's what ur in to. I moved to Mexico from Massachusetts, and I'm driving truck now. But cool stuff.

[@modestdaddy2000]

Well done. I’d say, based on this vid, the instructor is a good teacher. Clear and easy to understand information.

[@jm-xh4yz]

I love learning new things and this was insightful and easy to grasp. Diggin' the channel.

[@Delta6ICU]

I deal with flooding in my backyard stream by putting a second outlet higher up than the first. So when the water backs up to a certain height it automatically engages the second outflow which basically doubles the flow instantly, without any input. I would like to see a video about debris build up and the best way to deal with it. Thanks, great video.

[@shmmoon]

In Calgary we replaced a traditional weir (Harvie Passage) that is used for water diversion (and is attributed to deaths every year or so). The new system makes it navigable for people and wildlife. It might make an interesting addition to your next project. I love your videos. They are excellently crafted and well thought out. Thank you very much for this.

[@Duplicitousthoughtformentity]

I like that he introduces the sponsor, but saves it for later so we can learn first. Meanwhile every other channel on youtube demands likes, a subscription, and the nOtIfIcAtIoN bElL, then they throw a two minute long advertisement for their sponsor in before the actual video even starts, then they beat around the bush to stretch it to 11 minutes for that ad revenue, and they STILL demand that you throw money at them on Patreon. This guy kicks ass, glad to be a new subscriber

[@BrakerOfStones]

There’s an old one in tualatin that’s crumbled. It makes the river 1-2’ deep all the way across which is great little ripple maker and prevents anything but personal watercraft from accessing the area keeping it safer for families and fishing

[@markfrench2951]

Another good one - TY. I am using your videos as pre-view content for my undergrad civil engineering hydraulic lab course. Good connection to real-world application.

[@stedeestelle2866]

As a graduate civil engineering student, I am saddened to have discovered this channel only now, but nonetheless also delighted to have discovered it.

[@dialecticalmonist3405]

I'm not involved with civil engineering, but I am desperate to learn about it because I find it fascinating. I hate not knowing how the "stuff around me" works.

[@stedeestelle2866]

@@dialecticalmonist3405 that kind of enthusiasm and curiosity is sadly what many civil engineering students lack. A lot of students worry mostly about getting passing grades, and while some worry about actually learning the subject matter, only few bother to see and analyse the practical applications of the program. Kinda sad tbh, and I've been guilty of this, too, in the past

[@dialecticalmonist3405]

@@stedeestelle2866 That's sad. Because this is the stuff that makes an "economy" an economy. It makes a society a society. It makes an empire an empire. Every theoretical discovery in science, was created to ultimately improve the infrastructure of society, and just as often, pure intuitions from the necessity of infrastructure informed theoretical discovery. It's like the glue between the mental and the physical.

[@blankxd5837]

@@stedeestelle2866 true, I was guilty with it to. Especially early on when all of our subjects were just maths, physics and other non related stuff. It got interesting when we had designs subjects though.

[@scott247]

Weirs can also be used in the steel making process to help control the flow of molten steel. They are pre cast from a high temp cement called refractory. I surmise weirs can be utilized in many instances for greater control of a liquid.

[@ValeriePallaoro]

And that, my dear, is Practical Engineering.

[@RobSchofield]

Would love to hear something about scouring downstream of weirs, and how it is affected by weir type and flow.

[@eugenelim11]

Thanks for sharing. I love your explanations. They are simple and easy to understand, even for non-engineers. Once again, thanks for a very informative video. 😀

[@DanielMac1052]

Great to see a photo of the Burdekin Dam at 2:51. I live downstream of that dam and use it's water on our farms. A few weeks ago we had a large flood here and the dam was 6m over, equating to approximately 16000m^3 of water every second!! Pretty cool to see an Australian dam on a KZbin video, Thanks :)

[@gormster]

As an Australian, were you also humming Killing Heidi’s “Weir” the whole time you were watching the video?

[@krishdragnorax7324]

So youre saying that the photograph is upside down? Wow thanks!

[@rediculousdude]

Ayy another Aussie

[@andrewweir5345]

Practical Engineering: What is a Weir? Me: Me

[@anondeilvers91]

Absolute madlad.

[@Kai-ib4cn]

lmao

[@momos2790]

I see what you did there Mr.....Weir...lol

[@argentorangeok6224]

Related to Tom Weir?

[@dChad014]

Yo same

[@Vegatable]

This whole time I was thinking about the dangers! You should talk about boil points, different types of river hydraulics, and maybe even explain how rocks can create dangerous “holes”

[@RaisinDog]

Thanks. Like the physical models along with the formulas and verbal explanation

[@opforind]

There is a folded weir on the upper Delaware River built for the purpose of trapping eels. The trapper maintains and rebuilds it as needed by hand since it’s essentially a pile of river rocks.

[@ChickenTandies]

Took a break from studying for my fluid dynamics class to find this in my recommended. Thanks KZbin. Great vid btw

[@jaredh2341]

Found this interesting. I live in Minneapolis near the Mississippi River and it's cool to now know what these structures in the river are now.

[@ajmckay2]

Great video! My application is on the micro-scale. I have an aquarium with an overflow into a sump. I'm researching ways to make the ugly "overflow box" smaller while still providing enough waterflow so that the tank doesn't overflow.

[@LaGuerre19]

"Thank you for watching, and lemme know what you think." ... You know what I think, sir? This is the best channel I'm subscribed to on KZbin. Thank you for your hard work, and for making engineering so interesting. All the best.

[@maxximumb]

Grady, to gain a variable flow control, could you use the horizontal angle of a folder weir? If the point of the folded weir was say 5 degrees higher than the outer sides, a slow flowing river would only flow over the lowest parts of the crest. As the flow increased, more of the weir's crest is used by the water, This would effectively self regulate the weir's geometry.

[@Electroblud]

*commenting because I also wanna know the answer to that one* 🤓

[@a7i20ci7y]

I was thinking the same thing. Geometry such that as the water level rises, the length of the weir also rises.

[@Yora21]

Interesting thought. There probably is a reason why it isn't done. Or it actually is done. Otherwise you might just have made a possibly great invention.

[@maxximumb]

Does this image clarify matters? imgur.com/qsoManv

[@Tobsta1991]

Such structures exist and they're called compound weirs. These structures come in various cross-section geometries which can be tailored to provide better control of water levels under various discharge rates. The structures discussed with a fixed crest height, also have a fixed relationship between the upstream water level and discharge capacity.

[@zoleroid7027]

Weirs are a prime example of "form follows function" especially the piano key ones in my opinion

[@golikaviani5879]

This was fantastic. OGEE is my new word. You have an amazing voice (and depth of knowledge of course) for teaching.

[@geoffreywinfield7980]

I've seen many of these structures and even played around on them, but I hadn't ever really thought about their purpose, even though I have always had an interest in engineering (and in just about everything else, to be honest!). The vid took my attention straight away with the clear intro, and kept it throughout. The presentation was nicely modulated, smooth and professional. Well done. Recommended.

[@TamCloncey]

Awesome video work Grady! You've taught me a lot about civil engineering, concepts I wouldn't otherwise consider.

[@maerivery]

このチャンネルの動画たまにオススメで流れてくるんだけど毎回楽しませてもらってる

[@VedranPrema]

User friendly video, easy to understand, great visual tool and very educational. Thank you! Excellent work!

[@VaibhavSnehi]

your content makes engineering very interesting... I am happy that you are still posting!!

[@SleazyRay1974]

I'm going to try some of these shapes in my aquarium sumps to improve aeration

[@justinwideman3471]

You should do a video on the San Antonio river in San Antonio with all the locks, dams, under city tunnel and weirs down Mission Reach south of downtown.

[@howardbain6516]

The hydroelectric dam on lake Wissota, Wisconsin, USA is another variation of a weir. It has MASSIVE counterweights on it's weir gates allowing it to automatically control the level of the lake. Some engineering for almost 90 years ago.

[@Cadwaladr]

The first I ever heard of a labyrinth weir was when I saw a picture of the one in Waco on the Brazos river. I wondered why it was like that.

[@rongarza9488]

Thanks, Cadwaladr, I looked it up. Interesting problem: how to remove debris that clogs up the labyrinth weir. Did they ever solve that? First thought was to add hinges in order to occasionally reconfigure into a huge chevron in order to let the debris float to the banks. Just a thought.