Weirs | The COOL Engineering Behind Them 😎 

Sir, how was the zig-zag wier able to reduce the water level more than that in the planer version?

would u accept one time payment?

@@shyamtripathi2097 Hi, I didn't realise our audience would be so much interested to understand the physics behind the zig-zag weirs. I will definitely explain it in a dedicated video.

@@shyamtripathi2097 it is longer. Same as making river wider. Same as putting wider straight weir.

is this guy Indian?! I'm just curious, he has Indian accent

Exactly, wanted to comment this as well

Increased surface area... Change of shape...

Sorry for skipping the physics part of zig-zag weir. I didn't expect this much curiosity around this topic. We will definitely explain it in a different video.

If you explain the physics the videos won't seem so geared to school children..

there is an increased surface area for the water to flow over.

it's just a good explanation

Isnt everything like that😂

I am glad to know that :)

...you mean like literally anything?

Yeah, because that's so simple Europe has a strong push to build back thousands of weirs. Weirs aggravate floods wakes arrive faster and more violently downstream. The small city upstream is fine while the large city further downstream where 2 large creeks combine totally gets flooded without any warning time. The people just die in another legislature. Weirs are also terrible for the aquatic ecosystem. European Union removes weirs to increase drinoing water quakity and filtration. To redudce flood risk fron fast channled flows. They reestabkish natural flooding zones and create artificial rapids for the same flood protection effect. This concrete pouring promo tells youm like 10% of the complex truth. As a white warer kayaker I can tell you how boring concrete channeled rivers are compared to natural flows. I'm by no means into biology or ecology, the difference in wildlife is staggering in a river having weirs vs one with natural water flow regulation. There is very few places were such flood protection is essential and other means woukd not work. That's true for thunderstorm collecting basins or mountain zones where snowdrift piles up. Rare places that have frequent flash flood drainage events. Sites nobidy shouldnlive near the river anyways. Thanks to fertilizers and contraception we can start to move out of such dangerous areas. The need to pour them into concrete is basically gone. The benefit of a species protecting aquatic and floodzone habitat offsetting agricultural monocultures as wildlife reserves is way higher in priorities today. We have to offset fertilizer use. W/o natural habitats for bees and insects no food grows at all for humans. China has taken this experiment far enough that people have to manually fertilize the pollen on every apple tree blossom with a q-tip in some regions where bees are extinct. The most simple use of poured concrete is usually a terrible idea. Go ask some real experts first before engaging in such projects. It's not.that easy.

The increase of velocity on downstream can generate scouring on channel base, thus deepening the base of channel.

i think those are very good points. i had similar questions, you answered most of them, thanks. also: wouldn't there be a lot of erosion at the downstream side of the weir directly at the weir due to all the turbulence in the water? thinking about it, i recognized my cities weir has additional openings at the bottom and valves with wich they can regulate how much water is flowing over AND under/through the weir at the same time. why exactly would they build it that complicated? has to have a lot of advantages, doesn't it? i thought maybe more constant flow rates and clearence of the collected sediment at the upstream side of the weir or less erosion in general but those are just guesses.

1. It did slow down the upstream erosion though since the flowrate is slower

@yotonking2831 it is possible it did. One issue you can see and they did touch on this is the video is that the upstream sides water table changes. It could be 0 do to a high sided river bank, but it could be catastrophic like we see when a lake is formed. It's highly dependent on soil types and the nature of the installation.

i think it decrease vertical erosion but lateral erosion increase on upstream side. And in downstream side vice-versa. also it depends on topography and geology of rock.

@yotonking2831 it may have. It depends on the topography and mineral density of the substrate. If it floods, you can see erosion in different areas. If it pools and doesn't flood, it changes the water tables so it could have unforseen effects.

The animation quality is really cool

Length of the weir is diffrent.

It is because of “volume”. If you take the total “length” of the area that water overflows and multiply by the height of the overflow then you have the volume available. The velocity is how fast the flow rate must pass through that volume. AKA… a larger drain pipe. Using a zig-zag allows a longer “wall” within the width of the channel. Another alternative is to make a wider channel, but doing things like adding a curve/diagonal wall or waves/zigzags are more practical. The zigzag has other benefits when you consider the force of water applied to it.

Is it energy conservation? If the downstream river would be deep, the flow would be slow also, dispite the difference in potential energy.

@@paulfontaine7819 Interesting 🤔. My educated guess is that if the downstream river is deep, then there’s more mass of water so more inertia. Thus the kinetic energy of the water accumulated during the time of free fall (because of potential energy) will be lost to friction (so I guess heat?) with the bigger body of water downstream so the effects won’t be the same as when the water levels below are relatively low.

@4:30

The difference between weir and dam: Weir let water trough the crest, but dam forbid it. On dam, Water flow through the penstock (or tunnel), mainly for power generator. The height of water on dam is regulated

Dam are use for collecting water to power generator or supply, weir are use for prevent surge of water to downstream. Both are reservoir just structure difference

😂😂😅😅

Not sure what video you were watching….. 🤷🏼‍♂️

What's wrong with your username😂

@@iaashu98 Corn is a metaphor of tooth in korea 😄

Can you elaborate?

You CG it away

​@@karantekwani3660 sediment/silt (fine particles of dirt and minerals) builds up in layer's seasonally.

Most modern weirs and dams have openings at the bottom and from time to time they get opened to flush out the settlement. There are impressive videos from China where you see a turd like stream of soil getting flushed out from a dam.

@@FritzSchober so that's what those videos are 😂

Indeed. If the downstream river would be deep, the flow would be slow also, dispite the difference in potential energy.