Confined Aquifer Model

Confined Aquifer Model

Hi everyone welcome back to Cody’s lab. So today I want to try making a model of a confined aquifer. So what we’ve got here is the basin which is going to be holding the water and actually for the well, I’m gonna be using a bubbler stone connected to this clear tubing here So you basically got the hole in the ground – which is the well – and then down near the bottom where the aquifer is you got the filter pack. Ya know. This is to keep the sand from going into the hole. Now I’ve got some water that’s dyed blue so it’d make it easier to see. I’ve got some clay and Down by my feet are some buckets full of sand. So the sand is gonna be our water storage medium in the actual aquifer. Let’s start putting in the sand here So think of this like a river is currently depositing sand here Or gravel or something that is good at transferring water There’s our transmissive layer of sand Which can hold water. Now of course this probably in real life would be already full of water So let’s start adding the water here And now what we’ve got is an unconfined aquifer basically the water is only pressurized to you know atmospheric pressure and its own head height so with this type of aquifer all we have to do is dig a hole and The hole will fill up with water as the water comes in from the sand You know maybe you’ve got your river channel You know the water flows into the river channel because it’s a lower spot If I dig the sand away, you should be able to see that the water Level inside of our well bore here is about the same as the water level of the aquifer see if I pull water away you can see It’ll begin to drop and then the water comes back up It’s a little bit higher, and that’s due to capillary action, okay, so let’s push the sand back up against this Level this all out And now we need to add a layer of something that slows down the flow of water An aquitard. If I’m remembering my terminology correctly. Now clay is the obvious answer for what this aquitard will be made out of because clay Absorbs water and it makes it very difficult for the water to go through it. It forms an almost impenetrable layer now how you would get this is say the river meandered away and Then you start depositing smaller material or perhaps a lake formed And you get some sediment at the bottom of the lake But ultimately this forms a cap that the water has difficulty moving through this will confine that lower aquifer there Hence the name of confined aquifer Okay, now that I’ve got my clay layer in I’m gonna have to let this absorb water Which is going to be slow because water moves through clay slowly. I might even have to spritz in some from the top here I’ll give it an hour or two to get fully moistened So there’s the clay in and that’s thoroughly hydrated. I actually ended up adding a layer of bentonite you can see here just to make sure it seals very well, and you can already see a little something here See that, the water level has been pushed up Above the layer of clay That’s because the weight of the clay is now pushing down and since it’s heavier than water would be, it’s creating more … pressure. so now the pressure and this Aquifer is now high enough to actually force the water all the way out to the ground surface But the clay is holding it down so the water can’t just go right up through the clay Let’s turn this up to 11 and add another Aquifer on top up here. Let’s use a different colored sand shall we? I almost forgot, but let’s add a second well in here into the unconfined aquifer that we’re making this way we can compare the water height oh no, we got some water escaping Look at that the water has found its way up through clay That’s annoying It’s gonna ruin my test Is there a way I can plug this? Yeah, but Is there gonna be others like that? So I just filled all the empty spaces in the sand with water. In fact, I’ve now got standing water up here to the top So I guess this would be let’s call this a river channel right here a really wide river or something so the unconfined aquifer is just about even with the water table And the confined aquifer, has got the water pushed all the way up here Essentially what I’ve got here is an artesian spring or an artesian well. see? The water is naturally coming up out of the ground under pressure And I’ll be able to get a little bit of water down here You might be asking. “Where is this water coming from?” You see, water can’t flow down; like you can’t go from here passed the clay layer and then to here the water is coming from what was trapped in here the sand is compacting under the load But the water is actually forming just a little bit of the back pressure keeping the sand from compacting but as the water leaves the sand can compact and so the actual entire ground surface is dropping slightly as The water is being pumped out …or pumping itself out By the weight of the ground above it it’s able to do this because the sand has a higher density than water and you’ve got water in it but… The sand itself is so heavy It’s able to overcome the hydraulic gradient and force the water higher than you would normally expect And that’s actually pumping out quite a lot of water it makes sense you can store a lot of water this way, but These are very difficult to water back. These confined aquifers do recharge, but very slowly And usually not straight down or rather Water that’s coming out from maybe some mountains It just goes really deep and then tries to come back up. Once this ground is compacted. It’s not gonna just spring back naturally. Once this is compacted, It’s It’s lost your “store-ativity” forever. In many places of the world such as California This is a huge problem because those aquifers – which are being used because there’s a drought and they need the water… Are never gonna recover and the ground sinking can cause other problems as well. There’s a little bit of storage you can get at that point due to the compressibility of water itself, but it’s not very much. In fact, I think this is just about done Yeah So it’s compacted you could add more weight here And I could force more water out by compacting the sand tighter. Gonna push on the sand … Increase the pressure … then it’ll pop out Increasing the pressure does cause more water to force out so this sand isn’t fully compacted just yet That’s not really a practical thing to do Now for this unconfined aquifer. I actually have to do work to pump the water out. You might notice that The water here is a different color because I didn’t add the dye to it And also it’s a lot more murky murky It’s not a good water quality But that’s mostly just because of the type of sand I’ve got it with watch What happens when I’ve got some wells spaced out away from the pumping well Maybe call these ponds, but let’s just start pumping. I’m just gonna suck the water out with my mouth See the first one has already been emptied because it’s right next to the well See that? We should have a cone-shaped depression in the surface of the water What we’ve caused is a cone-of-depression. This whole area here is now without water the water has got to flow in from elsewhere and There might actually not be enough water to do that, so let’s just add the water back a little bit here We should start seeing the water come back. Yeah, so in this case it came Kind of off to the side here You can see that? that’s because the water has Trouble flowing through the sand it actually creates a resistance that slows this water’s flow down This means that if it’s close to the well the water can flow to it much quicker Also, the farther you get from the well the more volume of water you have within that radius and that’s how these confined aquifers can actually hold on to water even if the Clay layer above them doesn’t completely cap it off That’s because the water here has to move through the material to find a way out That’s why I had a little bit of time to work To actually pump a little bit of water out of it Because the water couldn’t just flow out instantaneously. A confined aquifer would also form a sort of cone of depression, but it’s not actually the water’s level But rather the potential head – a potentiometric surface – that gets drawn into a cone. So basically you have lower pressure near the well and higher pressure elsewhere I’m gonna try this again that is kind of fun watching the cone of depression expand out Here, let’s not pull out as much water out, so now I should be able to see them recover and stop pumping here Yeah there we go Alright This’s a lot of fun for me Not sure if I conveyed the information nearly as well as my geology teacher. But, I hope you enjoyed at least! and I’ll see you next time [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing] [Music Playing]

100 thoughts on “Confined Aquifer Model

  1. Another way to have this happen, if you live in the mountains is, the aquifer is on an incline. Rain drains into the aquifer from higher up, and pressure forces the water up the pipes.

  2. This channel comes in handy for my earth science class, like how I did a project about Indium and my teacher didn't even know what that was

  3. Question for you Cody, if you'd be so kind to enlighten!

    At 6.00 mins you talk about the ground pushing down continuously as the water is being drawn through the "artesian spring". Can earthquakes move this aquifer layer around therefore redistributing water if the aquifer layer becomes compacted?

    Either way I think long term i think the world has to move to sea water desalination. Although I suppose with the magnitude of consumers on the planet that would bring in problems with desalination of the ocean… Seems we are past the point of return already! Where do you think we should draw our water from? Whats the best solution?


  4. cool vid dude. Could i point out that when the tubing is lowered down, lower than the base of the well, you also create a gravity pump which would have increased the flow rate.

  5. So there is no way to refill a Confined Aquifer, not even by pushing the water down there with basicaly "Brute Force".

  6. Aquatards are people that drink energy drinks instead of water on an outside 110 f work site, then fall out from dehydration or heat exhaustion, or a heart attack, and stomp down the whole site while they are hauled off in an ambulance. Aquatard.

  7. you should've shown a perched aquifer as well. also the term aquaclude is another term you can use for aquatard. Also I wish you went into detail about the porosity/permeability of sand and clay that allows aquifers to form.

  8. I guess artesian water behave similarly, and here in my country we have a ton of that, but we fall in the same problem, draining to much, also unprofessional drilling mixes the artesian water with the soilwater, which makes it undrinkable.

  9. The confined aquifer is the most valuable commodity on earth. The single most poisonous substance ever cannot be filtered by any means

  10. Hey everyone, cody made a backup channel due to community guideline strikes. "Cody's lab backup" is the channel so go check out his update video! this channel is facing being deleted and he cants even post a video to warn people!

  11. When the drilling company drilled our well, they said we had enough water flowing to build a car wash… However, that water is not very good water, it has a lot of iron in it.

  12. Where I live we have a confined aquafer prolly ~4-6 m bellow the ground because we have a surface clay and stone layer with a thin topsoil layer, but it must be a lot more porous in the aquafer than sand or sandstone since when it rains a lot especially when tropical cyclones make landfall and dump rain on the range we can actually hear the water moving through it which is a bit scary, and a few years back during a flooding event in the wet season the ground in some places felt like a waterbed.

  13. Ok i want to know if say you had to drill through bedrock to get to water, and this bedrock is miles large, would their be a chance it is a confined aquifer or would it be getting water from other places and if being filtered through the sand and silt it travels?

  14. i wish more floridians would see this information…. the higher ups insist on pumping from the aquifers forever…

  15. So one might say that California's early unrestricted artesian water systems could be…the Cone of Shame?

  16. Hi Cody can you answer me how i can dissolve gold mixed with other metals as zinc,silver,copper and other inpourities.Thanks for your answer .

  17. Thank you for this video Cody. I live in Cape Cod MA. And this has helped me picture where our water comes from. All apparently from a large single aquifer.
    I was wondering one day which pond we get water from just cause cape I didn't know had aquifers

  18. you explained this really well and having the diarama really excellently helped…thankyou so much for doing this 🖒🖒🖒

  19. Hey thanks, Cody'sLab
    I was binge-watching ' under the dome' and they said something about using artesian wells to replenish their towns polluted water system – so my search brought me here.

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