I remember a presentation from Itaipu Dam staff mentioning the average lifespan of dams and what usually ends them, and what active steps they were taking to make sure their dam last much more than that - 140 years. Back then algae and mussels made headlines and they took the spotlight to mention silt
The yellow river of China often overflows with nutient rich silt and changes course, also flooding and destroying habitations. The name is due to it's silt color.
really depends on the river. Where i live everything is snow melt and comes down rocky rivers so theres little silt to contend with but for places like China most of their dams are fed by muddy rivers so they're filled with silt, it's why mountain streams are often clear but rivers like the Mississippi, Yellow river, Pearl river, and Amazon are all so milky.
You should check out Practical Engineering if you want to learn more, he has tons of videos on the topic of soils, hydrological forces, infrastructure, basically everything a civil engineer can speak on in a professional capacity. He's great, and he's covered a lot of individual major events as well, like when the Oroville Dam breached, and the resulting sedimentation issues that arose from that, as the breaching water cut deep gouges into the hillside from the rapidly surging water
@@GilmerJohn they have to dredge it because they put dams on it. It didn’t need dams and locks before the “ENGINEERS” came along. That river was around a lot longer than humans were, and did fine.
An Archimedes screw set at the dam on the upriver side can lift silt from the base and dump it out on the downriver side. This would need to be set up during dam construction and it would likely take a number per dam not just one but it would help with the removal by constantly removing silt. Since at the dam itself is where the silting first starts by keeping it low there you keep it dropping there so the rest of the catch basin doesn't get as silted.
Silt will still settle upstream of the screw even if you keep the area immediately next to the dam completely free of silt, the currents in a reservoir aren't that strong. If you de-silt only around the dam, you'll just end up with the dam sitting in a gently sloping hole, with the bulk of the reservoir still silted up.
@@kyousouka yup, but you have made the removal of the upstream silting less and have at the critical area a deep water supply. No matter what the purpose of the dam, it works best when there is deep water right near it.
The bypass tunnels seem to me to be a good method. You could build the dam like a bathtub with many drains. It would be very expensive but it may save money in the long run. They dug a bathtub-type drain in the bottom of Lake Mead with water in it.
Anaerobic digesters also suffer from silting up. Fre-energy from the UK use a rotating arm and a similar screw to remove sand, gravel etc. This contains valuable nutrients so is spread on fields as fertiliser. I imagine some reservoir silt could also be sold, especially if segregated.
I would like to add that there is a fourth option: just live with the fact that the dam has silted up. In Africa there are many 'sand dams' purposely constructed. They build a simple dam which in a few years completely silts up. The sediment behind the dam will still hold groundwater which can be used for irrigation and drinking water. The advantage of a silted-up dam is that the groundwater will not evaporate like the water in a reservoir.
Obviously not a help for hydro power, but what a great idea for water for drinking and irrigation! Groundwater depletion is a huge problem in many parts of the world (like the US Midwest, although we’re not feeling the impact yet), so the idea of retaining water in the silt behind dams could be very helpful.
Thanks for the insight! Interesting to know that in Africa sand dams are constructed like this. Just another unique way to battle reservoir silting! 🤔👍
the issue is the lack of water not just the silt build-up. I'm not sure what size you're referencing in your example but i would imagine this can't work for large dams like these. the issue with silt in large dam is the capacity. Once silt fills in they're not holding water rather displacing water because the water that would be stored there are released due to "over capacity". while your idea might work in medium to local scale dams, large dam that supply millions of people would suffer from a water crisis.
4:07 "A cargo ship passes sandbanks near Kabul, Germany during historically low water on the river Rhine." The nearest "Kabul" is a kebab restaurant an hours drive away. The photo is from a village called Kaub
Blame the website. It's not the fault of our dear deer. Neither is it the fault of the photographer, who tagged it correctly on the AP image marketplace.
The news clip about record low water levels in Germany has nothing to do with sedimentation or silt. The picture shows an iconic part of the Rhine river, which does not have dams. The nearest dam is app. 200 km upstream. The reason why commercial shipping had massive problems in the years since 2018 are the enormous summer droughts in western Europe. At this particular part, the river cuts through a mountainous region, the valley is narrow, the riverbed is solid rock. (The scenic valley is a tourist hotspot, btw). There is no silt. Interestingly there is the opposite of a sedimentation problem upstream. In the 19th century the river's meanders were cut off, creating shortcuts to prevent flooding and convert swamp into farmland. Since then, the river has cut deeply into the soft ground (there the riverbed is sediment), causing the groundwater table to drops significantly.
Australia developed a problem with agricultural land erosion.....which began to be addressed with the "land care" program to arrest erosion with trees and land contours. Land erosion really came into its own during the 1930's drought conditions, combined with economic hardship led to sever over grazing, which deprived entire regions of their top soil, which were thin and fragile.
Another problem is that the silt is very fertile when it is spread out on the land during floods but is useless sitting on the bottom of a reservoir. The Aswan dam comes to mind.
A lot of the causes of siltation are also causes of eutrophication, where a water body is essentially made unfavorable to life through a combination of vastly increased nutrient levels and algal blooms
@@argentum530 advanced eutrophication from farm run-offs was my main field of study, but I agree, I've actually followed a UA-cam channel where they're rebuilding a forest by flooding it to create a fresh slate to start a new forested wetland buffer, I think it's in Michigan?
I kinda wanna look up my old papers to give myself a refresh because one of my low impact/long term solutions was just to allow eutrophication to run it's course in specific areas like the farm pond silt buffer system, mixing it with long term watershed maintenance to allow the run-off to eutrophy fallow fields in a mix with old school crop rotation, but then the government here completely skinned our environmental assessment industry which was my main push in the end, and I got disillusioned and dropped out lol
Unless your dam is very poorly designed, silting up does NOT affect how much power can be generated. Only the storage capacity of the damn is affected. And so the only effect it can possibly have is running out of water to generate power with. Low water levels at a dam DO affect power generation, as the water pressure in the turbine is lower.
Matilija Dam, located in the Ventura River watershed on Matilija Creek near Ojai, was built in 1947 and silted beyond use by 1960s. A notch was cut in the dam for safety reasons but total removal remains beyond available funds. PS - Blocking river sediment has been blamed for a lack of sand replacement on local beaches. PS2 - Los Angeles retention dams mentioned as having been cleared of silt are specifically designed to catch water from extreme rainfall events and debris to prevent flooding downstream. Basins have to be cleared on a routine basis to maintain capacity.
For the time it remains, the "cut here" stenciling remains the best graffiti to see anywhere in the world. Considering how silted it is (so any new silt must go over the dam), my instinct is that the infrastructure of the 101 highway that protects what would be constantly eroding cliffs upcoast is a much larger factor in the ongoing beach starvation than is appreciated.
@@westrim - Good point re freeway limiting cliff erosion. Recently posted UA-cam video on bluff collapse at Torrey Pines, Black’s Beach in the San Diego area illustrate your point!
Having rafted in the Green River in Utah in spring some years ago I saw first hand the silting going on. I went for a swim and in a half hour the pants pockets were full of silt. Gave me some reflection on how much was going downstream to Lake Powell. I can only speculate how much silting is going on there as the Green and Colorado both go thru many miles of sedimentary rock before hitting the reservoir. It would be interesting to find out form people managing the reservoir how full of silt it is. (If they will admit to it).
You discovered another method of silt control. We just fill all the upstream rivers with swimmers to collect the silt in their pockets. Problem solved. (Apparently I'm in a strange mood.) Thanks for the story.
When I have my tinfoil hat on, a part of me believes the reason the lakes have such a low water levels is due to silt behind the dams. Silt will destroy a damn and I wonder if the experts believe the dams maybe in trouble due to the extreme amount of silt collected at the bottom and pushing on the dam. Are they worried about catastrophic failures at lake mead or lake powel? Food for thought.
@@MrNeptunebob Obviously Speedos should be outlawed. Anyone wearing Speedos should be arrested. Those damn dam cloggers should be prosecuted to the fullest extent of the law.
Silt is what is missing in agriculture on the fields quite often due to methods used. Not sure if it might be viable to prep dredged/dugg out silt with rotten plant cellulose to create humus for aggriculture. It would be i guess more cost effective to have better aggriculture methods in the first place that prevent fields to be washed away.
One of the other consequences of silt accumulation in dams is that they create "hungry rivers" downstream. Flowing waters have a certain amount of stream power, which carry sediments. If the water flowing out of a dam no longer holds sediment (because it got dropped behind the dam), it's going to pick up sediment downstream of the dam. This increases erosion downstream, which can have serious knock-on effects to anything that is near the river downstream. So siltation is not just a problem at the dam. It's also a problem downstream of the dam.
Small point, Pressure waves travel long distances underwater very quickly, meaning underwater explosions can injure susceptible sea life far the explosion. So Air bubble curtains are used for acoustic dampening, not to drive away sea life.
Another issue with dams stopping silt from moving down the river, that you didn't talk about as much, is it causes high erosion downstream from the dam.
@Asianometry We too have a problem with reservoir silting in Pakistan. Our major rivers carry a lot of silt for example the Indus and Jhelum. Our 2 biggest dams (Tarbela and Mangla Dams) have been continuously silting hence their reservoir boundaries have to be periodically raised to keep up the storage capacity.
@@Theoryofcatsndogs The forex reserves are at an all-time low. The economy is in shambles thanks partly due to the floods and lenders/donors are being very strict on lending money to our government as we won't have the capacity to pay them pay. There have been some international pledges for recovery and flood relief. Let's see what happens. The areas directly affected by the flood are mainly the rural areas of Balochistan, Sindh, Southern Punjab and certain areas in the KPK (formerly the North-West Frontier province).
@@reticentsimmer I'm sorry to hear that Irfan, with the war in Ukraine other very important matters have been pushed to the side. Wish you the best. 从 m
@@reticentsimmer Rubbish!!! Pakistan is such a rich country that it can afford to manufacture thermonuclear weapons and their corresponding delivery systems. A poor country would have used their nuclear knowledge to rather build atomic power stations!
The forest fire, followed by flash flooding, filled the riverbed, and now the water goes wherever it wants in the Santa ynez water Reservoir Canyon, Pacific Palisades, California
I first became aware of the silting problems when watching reports about an experiment with Glenn Canyon Dam in Northern Arizona. They conducted an experiment to see if a carefully managed release could restore some of the flood runoff benefits to the soil around the river channel. Turns out that this didn't go as planned but it did lower the level of the reservoir enough that you could see that there were large volumes of sediment in some areas of the reservoir. One of the most effective areas for sediment control in this area seems to me to be the Salt River system of dams outside Phoenix. The water flowing into the reservoir comes from two sources. One of these is dry two-three months out of the year. The other takes a pretty lazy path downhill from the eastern part of the state so doesn't really have a chance to pick up much velocity anyhow. The big concern, before the dams were built. was flood from rain and snow runoff on the watershed. A half inch of rain on the watershed could push the river beyond its banks as it passed through Phoenix because it would load washed and draws that were normally dry and that's where a lot of the silt came from. Otherwise, now, first, this river has to pass over a weird dam originally used to divert water into a power plant at the Roosevelt dam. This slows the water heading into the reservoir considerably so most of it comes out fairly clean. The water then has to make its way down to to Roosevelt dam's outlet, several miles away further on down. Then it passes into a second reservoir, then a third, then a fourth, then finally a diversion dam at the northeast edge of town that feeds water into the local irrigation canals, typically claiming all the water released upstream from that and a second system. So before the downstream dams were built in the 1920s and 30s, and before concrete lining of these canals, cleaning out the canals and irrigation ditches was an ongoing process. Now, there are occasionally rocks about 6-12 inches around that find their way into the canals but the water normally carries nothing more than algae and other growth rather than silt and that's the only reason the water isn't actually clear. So it was serendipitous that the way the system of reservoirs were constructed resulted in very clean irrigation water and reduced silting of everything, allowing it to last for 100 years with no reports that there are any real problems with capacity.
At 5.59 or have a pre settling reservoir to trap the majority of the silt before it reach the main dam and easier to get rid off....yes I know it will not clean the lot but it will increase the use of the dam by decades.....then every so often empty the dam and truck out the silt to start another cycle to prolong the dam utility...
Shout out to Cogswell Reservoir on the West Fork San Gabriel River in southern California! I love riding my bicycle up there: the roadway in is closed to normal vehicle traffic and is a lush, tranquil place year-round.
Why not use underwater vacuum hoses powered by the hydraulic head, especially when the opportunity to leverage all the excess energy and capacity during storms that will overfill the Dam. During construction a network of pipes with a grid of inlets that can be selectively opened one at a time could be used later to clear silt. If there isn't enough suction, a venturi powered by dam outlet flow could boost it. What is the economic value of all the silt, and quit it be used for something?
Super interesting, Lake Okeechobee in Florida is also facing siltation though for a different reason. Historically the lake was ringed by shallow seasonally submerged grass flats. The shallow lake would accumulate silt but in heavy storms the winds would push water and silt into the grass flats where it would get trapped. The silt is heavy in organic matter and has created some of the richest most fertile tropical peat lands. The lake is now rimmed with a levy that prevents the silt migration and the grasslands are now all agriculture mostly Sugar Cane.
Silt can also block harbours. Specially older harbours founded in a time when depth was not the primary driver, and storm shelter often was more important. A famous example in Europe is Belgian Bruges, a medieval prosperous town with a harbour. It lost a functional harbour that routed a high percentage of Northern European trade due to silting. Because of that however, the architecture survived and now it is is tourist town. In modern times, even the North Sea is dredged to allow Brazilian iron ore vessels to reach Rotterdam. (these largest class of ships only go to certain Chinese deep sea harbours and Rotterdam)
The flip side of this situation is the fact that dams increase coastal erosion. The silt and sand that would go to building beaches and marshes is trapped behind the dams and causing problems with them.
@Acceleration Quanta That's not what happened when the dams on the Elwa river in Washington state. The mouth of a river is a long way from the bottom of the ocean.
I would suppose that is why Norwegian Hydro power is so effective. The dams are in the highlands where there is very little soil. There is quite a bit of mineral accumulation that probably does some damage to the turbines. Quite a lot of silica due to the bare mountains I believe.
Not mentioned here is the role of silt in the prevention of coastal erosion. The Amazon dumps around 3 cubic kilometers of silt in to the ocean every year. Prevent that silt from flowing and you change the entire east coast. Recent coastal flooding in Asia for example was made worse by the lack of silt transported in the decades earlier. It has to be said however, that there had been very little done to mitigate the problem of siltation. Bottom line: We want that silt downriver, not in the dams.
I once camped atop a silted dam for a back country project. We drank filtered water from a pit we dug in the silt. It was the worst water I had ever tasted, full of tannins and who knows what, clogged our filters almost instantly. We were finally relieved by a storm that caused some streams to flow. Now I work at a mine where I see this effect on a fractally small scale on a daily basis.
In Pasadena CA there are two dams that are heavily silted. Both are on the Arroyo Seco. Not a river (only when it rains), but more like it's Spanish name suggests; arroyo: stream/brook. There's the Devil's Gate Dam, it's been dredged for the last few years. Mind you that Southern California doesn't get much rain. During the summer there's hardly any water. Making it easier to haul away all that silt. But when it does rain there is so much silt that comes down the mountain. Then a few miles upstream is the Brown Mountain Dam, built in 1943, according to it's website. It's a rather small dam. The website says that it's 81ft high. If you hike up to the dam now you will see that it's silted all the way to the top. If you're from the area do yourself a favor and make the hike. There's not much of an elevation gain, I think it's only 500ft over 2 to 3 miles. It's hardly felt.
Thank you for this uncommon type of information about civil engineering. I appreciate your work in educating your followers on critical pieces of infrastructure - industrial, civil, or otherwise. Greetings from the UK, Anthony
One solution would be to have a pre dam dam that lowers the speed of water and is designed to be easy to clean of sediment. But it is expensive and long term
I don't think dredging is that expensive, especially if it's just once per 50 years. You can do it from floating riverboats to reach everywhere in the reservoir bed. I think the real problem with this stuff is that most dams are the small cheap versions that exist at almost every river, often unregistered and old, and they piled up with crap that made them useless by now. Will take massive re-industrialization effort to go fix up all those.
Silt is really a problem called a loosing battle in the dam. In my region there is a river with 8 power plants and 2 flood dams. At first nobody really payed attention to silt, but 30 years ago a major drought revealed that there is no storage anymore. Since then there is constant work on the silt problem, and no matter what they do, they barely maintain the level or maybe advance by little bit year over year. Last estimate was they restored around 5% of the storage capacity.
What about them benifits? A silted dam becomes a piece of flat land with deep and very fertile soil. As for a hydro electricity dam, a silted dam will effectively always be high.
4:31 yeah .. but you know what its really really good for? plowing into unproductive sandy solid to make it more fertile and to plowing into farm land or mixing with green waste for compost (presumable) also maybe the guy from Dubai could suck it up for there land reclamation instead of steal other peoples sand...
Interesting topic. I don't know how accurate the claim is, but allegedly, China's huge 'Three Gorges' dam on the Yangtze river will become silted within ~50 years due the high degree of silt coming from upstream. What's worse is that the silt contains a LOT of pollution.
Have we considered simply exploding the silt? On a more serious note, I wonder if, keeping this in mind, it would make sense to build dams in pairs, with the expectation that only one would be fully operational at a time. Then, when the one in operation needs to be desilted, the other one can 'take up the slack' by being put into operation. I mean, there are no silver bullets, but just something that came to mind. Edit: That's what I get for not waiting until the end of the video!
12:17 lol sort of almost one one of thos massive bucket wheel excavators they use in german for lignite coal and then just have it automated to run up and down the side of the lake just constantly digging away lol
Yep, there was a recent job done to prevent silting at the Zengwen reservoir. It also has a connection to another reservoir, I guess it is the Wushantou?
There is a simple, inexpensive fix for this problem that would decrease silting by one or two orders of magnitude (10 to 100 times less). Simply ensure that beavers occupy as much of the catchment of these dams as possible. Their ponds collect the sediment and turn it into valuable 'bottom land'. And they do so much more. They a) reduce flood peaks and increase low water flows, b)direct water underground where it is save from evaporation, c)store much more water than is in the pond itself by raising the water table in the surrounding area, d) greatly increase biodiversity in their area, e) remove nutrients from the water and on and on it goes.
I like how varied your content is, I use to watch your videos about industrial topics, but now I enjoy your videos even though I can’t predict what the next topic is
The fact we know about it and implement nothing to get rid of the problem. Like why cant we add a door at the bottom or multiple doors that we open 1 or 2 times a year for a short time to get rid of extra dirt behind dam walls.
"Dead Storage". I just thought applied to the Hoover Dam and Lake Mead, near Las Vegas. Last year, due to the prolonged drought, they found quite a few dead bodies there. You know Las Vegas & the mob connection.
5:40 Years ago the lower Mississippi River had this problem. Someone offered a fix for a low price which would be paid upon completion. They accepted it and he fixed their problem. The same basic solution of rerouting the flow like sweeping with a broom can probably be used here.
This is a major problem in my state (MS) in the US. MS has several large flood control dams and deals with a lot of rain and lots of fine alluvial sediment. It keeps the army corps of engineers here who manage these quite busy.
I spent a summer hiking in the canyons of Utah. I got to see, first hand, the damage silting does to a number of small reservoirs. Take into account that many of the places that are good for dams are not very accessible to heavy machinery. It's a complex problem.
Agriculture has been dealing with the issue of silting for over 100 years in Australia, possiblity many hundreds in other countries, we use smaller settling ponds that catch water and gradually let's it flow into the main reservoir via channels or pipes, the smaller ponds dry up quickly and are easily cleaned in a day or 2 with heavy machinery. In the case where it is not dry you can transfer the water via diesel pumps.
i would expect a dam to have smaller gates on the bottom that would open for a short period of time once every few years to wash the silt out and then close
Ikr? My mind can’t get over why this is so hard. They got all the energy from the dam they need to do any engineering solution. Huge automatic rotating shovels. Whatever, sheesh. Like 13:10 the romans flushed it out. Wtf is that so hard?!
@@TheBooban yea i mean there is alot of lost technologies from ancient times. like the aztecs and mayans 100% had tech that was lost to the epidemics that killed 90% of them. also the tech the egyptians used to build the pyramids. roman concrete still hasnt been reverse engineered. also "atlantis" and all that stuff noone knows where it went other thaan it probably got wiped out ~12k years ago when the sahara went to desert because of the cycle where it gets lush every 5k years then back to desert 5k years later
@@ghostbirdlary I was just talking about this with a friend. Also, when you realize ancient cities had, in many cases, only 200,000 people, 500,000 people, and it makes you think wow they achieved all these things without needing tens upon hundreds of millions of people.
@@stevens1041 yea except like there was one in south america with an estmated 3 million people i think. and "atlantis" was estimated to be like 1 million
Very cool video, I was not expecting such a subject to be tackled on this channel. For anyone else who might have been pleasantly surprised by how interesting this video was, I can suggest the channel Practical Engineering. The host Grady offers some very interesting material about everything concerning our constructed environment.
I like Grady’s channel, but I don’t recall a video showing this aspect of water engineering, he focuses on the hardware and physics behind it, not really on the long term consequences. I can’t think of a channel off hand to recommend but I’ve learned many times more about the entire cycle and effects from other sources.
Asianometry Another cool topic about silt is how it makes clay! You could do a whole video about clay pottery history in asia, briefly tied in with the composition of clay. Love your videos, keep them coming!
I wonder... I saw one of the dams open spillway and spew tons of mud. What would happen if near the bottom of the dam we would make an optional spillway that opens on a regular basis, but just a thin flat thing, not very big. Open it just enough, so silt goes, close when you see water. Repeat every few days. With enough level difference, water would fill the hole with new silt, and you should reach some kind of equilibrium state. especially if currents would be engineered to pass over that thing, and leave all the silt incoming. Anyone knows any issues with that ?
Elk river Minnesota opens up the dams every several years to drain the lake and dig silt out and put it back in the fields. Usually only takes the summer, but not more than a year.
By Louisville Kentucky they used to have a incline belt for mining gravel out of the river perhaps that could help replenish farm lands if not to polluted
Oh yeah that makes sense. Usually during springs our local reservoir opens the gates to let through the copious amounts of water from melting snow, at the same silt gets moved too I assume.
This was very interesting. I know absolutely nothing about dams, nevermind the silting of said dams. With that said, the creator made a video that was still interesting and easy for a layman to follow. Good work all around.
Oh I just saw a short video demonstrating this whole video. Someone was showing how a dam works but after putting a sponge into a clear container that had water flowing from left to right, they added in small sedimentary sand after the water levels changed. I wasn’t sure it would be that bad on a larger scale but it looked like it wouldn’t be good even on a scale as big as your hand. First everything slowed down (mind you the initial flow of the water and sand was fast already) then it all slowed down, flooded till it was level, and as he added more sand, it all flushed out and even went faster than before. I feel like it’s a video someone found and just said “this is how a dam works” but I don’t think that was the original purpose of that video now. Wish I had the link from Instagram, I’d post it here.
We have a major issue with silting on the lower parts of the Columbia River caused by volcanic ash still coming down the tributaries from the 1981 Mt St Helens eruption. They have to hydraulically dredge the river yearly to keep the shipping channel open.
Near Angkor temple in Cambodia, there're 2 large man made reservoir built a thousand year ago: east Baray & west Baray. The east Baray is 90% filled with sediment while the larger west Baray is not. Wonder why they don't behave the same way.
West Baray also had issues in monsoon failure 500 years ago. Either way, artificial irrigation channels eroded downwards forming rivers, and so each tree ring shows varying over / under irrigation.
Older dams never had this designed in..and you would only scour out the silt right up at the dam... If you had the desilting passages built in at construction... and a huge armoured flexible pipe with a powered "pool cleaner" at the far end... you could do far better?
@@JohnSmith-yv6eq I'm a software engineer, just wondering :) thanks for your thoughts. I realize that silt is probably abrasive and no fun for metal pipes.
4:11 A cargo ship passes sandbanks near Kabul, Germany during historically low water on the river Rhine. The chances of getting stabbed in Germany may be similarly high, but the last time I checked Kabul was not in Germany.
Some tree huggers would recoil at introducing species that bottom feed. Our drought in the American Southwest is a good opportunity to evaluate such problems. When the waters return, could hydraulic dredging from pontoons onto accompanying pontoons allow water to flow over the 'filling' pontoon and 'that' pontoon be ferried to a location where the silts/soils/gravels be removed to some sort of gravel operation to separate and sent to beneficial uses? Just saying . . .
You should read Cadillac Desert. People need to watch the videos about removing the dams on the Elwa River....silt and wood are critical to near shore habitat where the rivers enter the oceans....off river channel storage is probably the best solution.
No idea silting claimed that much of a reservoir capacity each year…
I remember a presentation from Itaipu Dam staff mentioning the average lifespan of dams and what usually ends them, and what active steps they were taking to make sure their dam last much more than that - 140 years. Back then algae and mussels made headlines and they took the spotlight to mention silt
Silt is HUGE. Where water slows down sediment will fall. Even dust will eventually fall somewhere.
The yellow river of China often overflows with nutient rich silt and changes course, also flooding and destroying habitations. The name is due to it's silt color.
really depends on the river. Where i live everything is snow melt and comes down rocky rivers so theres little silt to contend with but for places like China most of their dams are fed by muddy rivers so they're filled with silt, it's why mountain streams are often clear but rivers like the Mississippi, Yellow river, Pearl river, and Amazon are all so milky.
YOu have no idea bout anything I am so disgusted
I simply had no idea how interesting dirt could be. Dude you rock!
Wait long enough and the rock will become dirt. :P
@@nitehawk86
Well played !!
look up Mud Wizard
He has some pretty solid points. its a problem of volcanic proportions and we need concrete solutions and some igneous thinking
You should check out Practical Engineering if you want to learn more, he has tons of videos on the topic of soils, hydrological forces, infrastructure, basically everything a civil engineer can speak on in a professional capacity. He's great, and he's covered a lot of individual major events as well, like when the Oroville Dam breached, and the resulting sedimentation issues that arose from that, as the breaching water cut deep gouges into the hillside from the rapidly surging water
Absent dredging, all lakes, reservoirs, etc, are temporary. A lot of meadows start as lakes - get filled up, filled in, etc.
So? Most of the navigable Mississippi and tribs. is routinely dredged. Just do it.
@@GilmerJohn they have to dredge it because they put dams on it.
It didn’t need dams and locks before the “ENGINEERS” came along.
That river was around a lot longer than humans were, and did fine.
This is not true in any stretch of the imagination. Most lakes and rivers are not dredged. Where are you picking up your info from?
Jon slowly working their way to making a video about everything that has the word yield associated with it
Nukes coming next? Ngl that would be a match made in heaven :)
"Today we look at the strange history of the triangular, and intriguing, Yield sign, common to American streets."
need to change his channel name soon, i’d say yieldonometry
"today we're going to synthesize schedule 1 drugs, our procedure has a 92% yield"
Doubtful since he doesn't understand what a meter is. 2,700 mm? Probably should be using inches if he's going to be a grifter.
An Archimedes screw set at the dam on the upriver side can lift silt from the base and dump it out on the downriver side. This would need to be set up during dam construction and it would likely take a number per dam not just one but it would help with the removal by constantly removing silt. Since at the dam itself is where the silting first starts by keeping it low there you keep it dropping there so the rest of the catch basin doesn't get as silted.
Silt will still settle upstream of the screw even if you keep the area immediately next to the dam completely free of silt, the currents in a reservoir aren't that strong. If you de-silt only around the dam, you'll just end up with the dam sitting in a gently sloping hole, with the bulk of the reservoir still silted up.
@@kyousouka yup, but you have made the removal of the upstream silting less and have at the critical area a deep water supply. No matter what the purpose of the dam, it works best when there is deep water right near it.
@@kyousouka good thought
The bypass tunnels seem to me to be a good method.
You could build the dam like a bathtub with many drains.
It would be very expensive but it may save money in the long run.
They dug a bathtub-type drain in the bottom of Lake Mead with water in it.
Anaerobic digesters also suffer from silting up. Fre-energy from the UK use a rotating arm and a similar screw to remove sand, gravel etc. This contains valuable nutrients so is spread on fields as fertiliser. I imagine some reservoir silt could also be sold, especially if segregated.
This video essay superseded my Dam engineering class back at the college, can't be more didactic than that! Kudos to you
I would like to add that there is a fourth option: just live with the fact that the dam has silted up. In Africa there are many 'sand dams' purposely constructed. They build a simple dam which in a few years completely silts up. The sediment behind the dam will still hold groundwater which can be used for irrigation and drinking water. The advantage of a silted-up dam is that the groundwater will not evaporate like the water in a reservoir.
Not so good if you want your dam to generate electricity though.
Obviously not a help for hydro power, but what a great idea for water for drinking and irrigation! Groundwater depletion is a huge problem in many parts of the world (like the US Midwest, although we’re not feeling the impact yet), so the idea of retaining water in the silt behind dams could be very helpful.
Somehow you made mud fascinating 👍 Great illustration for your concept of how blasting would work! 😆😂🤣
Thanks for the insight! Interesting to know that in Africa sand dams are constructed like this. Just another unique way to battle reservoir silting! 🤔👍
the issue is the lack of water not just the silt build-up. I'm not sure what size you're referencing in your example but i would imagine this can't work for large dams like these. the issue with silt in large dam is the capacity. Once silt fills in they're not holding water rather displacing water because the water that would be stored there are released due to "over capacity". while your idea might work in medium to local scale dams, large dam that supply millions of people would suffer from a water crisis.
4:07 "A cargo ship passes sandbanks near Kabul, Germany during historically low water on the river Rhine." The nearest "Kabul" is a kebab restaurant an hours drive away. The photo is from a village called Kaub
Blame the website. It's not the fault of our dear deer. Neither is it the fault of the photographer, who tagged it correctly on the AP image marketplace.
The news clip about record low water levels in Germany has nothing to do with sedimentation or silt.
The picture shows an iconic part of the Rhine river, which does not have dams. The nearest dam is app. 200 km upstream.
The reason why commercial shipping had massive problems in the years since 2018 are the enormous summer droughts in western Europe.
At this particular part, the river cuts through a mountainous region, the valley is narrow, the riverbed is solid rock. (The scenic valley is a tourist hotspot, btw). There is no silt.
Interestingly there is the opposite of a sedimentation problem upstream. In the 19th century the river's meanders were cut off, creating shortcuts to prevent flooding and convert swamp into farmland. Since then, the river has cut deeply into the soft ground (there the riverbed is sediment), causing the groundwater table to drops significantly.
Australia developed a problem with agricultural land erosion.....which began to be addressed with the "land care" program to arrest erosion with trees and land contours. Land erosion really came into its own during the 1930's drought conditions, combined with economic hardship led to sever over grazing, which deprived entire regions of their top soil, which were thin and fragile.
Another problem is that the silt is very fertile when it is spread out on the land during floods but is useless sitting on the bottom of a reservoir. The Aswan dam comes to mind.
A lot of the causes of siltation are also causes of eutrophication, where a water body is essentially made unfavorable to life through a combination of vastly increased nutrient levels and algal blooms
Neat to see that farm ponds serve a double purpose, filtering out excess nutrients through their ecosystems and collecting silt
The end result of eutrophication is a meadow, which harbors many forms of life and can eventually become a forested area.
@@argentum530 advanced eutrophication from farm run-offs was my main field of study, but I agree, I've actually followed a UA-cam channel where they're rebuilding a forest by flooding it to create a fresh slate to start a new forested wetland buffer, I think it's in Michigan?
I kinda wanna look up my old papers to give myself a refresh because one of my low impact/long term solutions was just to allow eutrophication to run it's course in specific areas like the farm pond silt buffer system, mixing it with long term watershed maintenance to allow the run-off to eutrophy fallow fields in a mix with old school crop rotation, but then the government here completely skinned our environmental assessment industry which was my main push in the end, and I got disillusioned and dropped out lol
@Acceleration Quanta Christ you're daft
Unless your dam is very poorly designed, silting up does NOT affect how much power can be generated.
Only the storage capacity of the damn is affected.
And so the only effect it can possibly have is running out of water to generate power with.
Low water levels at a dam DO affect power generation, as the water pressure in the turbine is lower.
Matilija Dam, located in the Ventura River watershed on Matilija Creek near Ojai, was built in 1947 and silted beyond use by 1960s. A notch was cut in the dam for safety reasons but total removal remains beyond available funds.
PS - Blocking river sediment has been blamed for a lack of sand replacement on local beaches.
PS2 - Los Angeles retention dams mentioned as having been cleared of silt are specifically designed to catch water from extreme rainfall events and debris to prevent flooding downstream. Basins have to be cleared on a routine basis to maintain capacity.
For the time it remains, the "cut here" stenciling remains the best graffiti to see anywhere in the world.
Considering how silted it is (so any new silt must go over the dam), my instinct is that the infrastructure of the 101 highway that protects what would be constantly eroding cliffs upcoast is a much larger factor in the ongoing beach starvation than is appreciated.
@@westrim - Good point re freeway limiting cliff erosion. Recently posted UA-cam video on bluff collapse at Torrey Pines, Black’s Beach in the San Diego area illustrate your point!
PS2 = PPS, "Post Post Script"
Having rafted in the Green River in Utah in spring some years ago I saw first hand the silting going on. I went for a swim and in a half hour the pants pockets were full of silt. Gave me some reflection on how much was going downstream to Lake Powell. I can only speculate how much silting is going on there as the Green and Colorado both go thru many miles of sedimentary rock before hitting the reservoir. It would be interesting to find out form people managing the reservoir how full of silt it is. (If they will admit to it).
You discovered another method of silt control. We just fill all the upstream rivers with swimmers to collect the silt in their pockets. Problem solved.
(Apparently I'm in a strange mood.) Thanks for the story.
When I have my tinfoil hat on, a part of me believes the reason the lakes have such a low water levels is due to silt behind the dams. Silt will destroy a damn and I wonder if the experts believe the dams maybe in trouble due to the extreme amount of silt collected at the bottom and pushing on the dam. Are they worried about catastrophic failures at lake mead or lake powel? Food for thought.
@@ddegn But what if all the swimmers wore Speedos? Can't collect silt that way.
@@MrNeptunebob Obviously Speedos should be outlawed. Anyone wearing Speedos should be arrested. Those damn dam cloggers should be prosecuted to the fullest extent of the law.
Your videos are the equivalent of a 3am Wikipedia deep dive about a random yet highly interesting topic.
Dams may provide renewable-resource services (water storage, flood control, hydroelectricity), but dam SITES are not a renewable resource.
Silt is what is missing in agriculture on the fields quite often due to methods used. Not sure if it might be viable to prep dredged/dugg out silt with rotten plant cellulose to create humus for aggriculture. It would be i guess more cost effective to have better aggriculture methods in the first place that prevent fields to be washed away.
If you look at satellite photos of Lakes Mead and Powell on the Colorado you can see all the silt since they are so low.
One of the other consequences of silt accumulation in dams is that they create "hungry rivers" downstream. Flowing waters have a certain amount of stream power, which carry sediments. If the water flowing out of a dam no longer holds sediment (because it got dropped behind the dam), it's going to pick up sediment downstream of the dam. This increases erosion downstream, which can have serious knock-on effects to anything that is near the river downstream.
So siltation is not just a problem at the dam. It's also a problem downstream of the dam.
Small point, Pressure waves travel long distances underwater very quickly, meaning underwater explosions can injure susceptible sea life far the explosion. So Air bubble curtains are used for acoustic dampening, not to drive away sea life.
Another issue with dams stopping silt from moving down the river, that you didn't talk about as much, is it causes high erosion downstream from the dam.
@Asianometry We too have a problem with reservoir silting in Pakistan. Our major rivers carry a lot of silt for example the Indus and Jhelum. Our 2 biggest dams (Tarbela and Mangla Dams) have been continuously silting hence their reservoir boundaries have to be periodically raised to keep up the storage capacity.
You guys doing ok in the flood?
@@Theoryofcatsndogs The forex reserves are at an all-time low. The economy is in shambles thanks partly due to the floods and lenders/donors are being very strict on lending money to our government as we won't have the capacity to pay them pay. There have been some international pledges for recovery and flood relief. Let's see what happens. The areas directly affected by the flood are mainly the rural areas of Balochistan, Sindh, Southern Punjab and certain areas in the KPK (formerly the North-West Frontier province).
@@reticentsimmer I'm sorry to hear that Irfan, with the war in Ukraine other very important matters have been pushed to the side. Wish you the best. 从 m
@@reticentsimmer Rubbish!!!
Pakistan is such a rich country that it can afford to manufacture thermonuclear weapons and their corresponding delivery systems. A poor country would have used their nuclear knowledge to rather build atomic power stations!
@@reticentsimmer dont worry muti allah world i here usa and china will bail you out americau akbar
another grrrreat video. thank you for all the work, and then sharing.
The forest fire, followed by flash flooding, filled the riverbed, and now the water goes wherever it wants in the Santa ynez water Reservoir Canyon, Pacific Palisades, California
I first became aware of the silting problems when watching reports about an experiment with Glenn Canyon Dam in Northern Arizona. They conducted an experiment to see if a carefully managed release could restore some of the flood runoff benefits to the soil around the river channel. Turns out that this didn't go as planned but it did lower the level of the reservoir enough that you could see that there were large volumes of sediment in some areas of the reservoir.
One of the most effective areas for sediment control in this area seems to me to be the Salt River system of dams outside Phoenix. The water flowing into the reservoir comes from two sources. One of these is dry two-three months out of the year. The other takes a pretty lazy path downhill from the eastern part of the state so doesn't really have a chance to pick up much velocity anyhow. The big concern, before the dams were built. was flood from rain and snow runoff on the watershed. A half inch of rain on the watershed could push the river beyond its banks as it passed through Phoenix because it would load washed and draws that were normally dry and that's where a lot of the silt came from. Otherwise, now, first, this river has to pass over a weird dam originally used to divert water into a power plant at the Roosevelt dam. This slows the water heading into the reservoir considerably so most of it comes out fairly clean. The water then has to make its way down to to Roosevelt dam's outlet, several miles away further on down. Then it passes into a second reservoir, then a third, then a fourth, then finally a diversion dam at the northeast edge of town that feeds water into the local irrigation canals, typically claiming all the water released upstream from that and a second system.
So before the downstream dams were built in the 1920s and 30s, and before concrete lining of these canals, cleaning out the canals and irrigation ditches was an ongoing process. Now, there are occasionally rocks about 6-12 inches around that find their way into the canals but the water normally carries nothing more than algae and other growth rather than silt and that's the only reason the water isn't actually clear. So it was serendipitous that the way the system of reservoirs were constructed resulted in very clean irrigation water and reduced silting of everything, allowing it to last for 100 years with no reports that there are any real problems with capacity.
At 5.59 or have a pre settling reservoir to trap the majority of the silt before it reach the main dam and easier to get rid off....yes I know it will not clean the lot but it will increase the use of the dam by decades.....then every so often empty the dam and truck out the silt to start another cycle to prolong the dam utility...
Bedankt
Shout out to Cogswell Reservoir on the West Fork San Gabriel River in southern California! I love riding my bicycle up there: the roadway in is closed to normal vehicle traffic and is a lush, tranquil place year-round.
Why not use underwater vacuum hoses powered by the hydraulic head, especially when the opportunity to leverage all the excess energy and capacity during storms that will overfill the Dam. During construction a network of pipes with a grid of inlets that can be selectively opened one at a time could be used later to clear silt. If there isn't enough suction, a venturi powered by dam outlet flow could boost it. What is the economic value of all the silt, and quit it be used for something?
Super interesting, Lake Okeechobee in Florida is also facing siltation though for a different reason. Historically the lake was ringed by shallow seasonally submerged grass flats. The shallow lake would accumulate silt but in heavy storms the winds would push water and silt into the grass flats where it would get trapped. The silt is heavy in organic matter and has created some of the richest most fertile tropical peat lands. The lake is now rimmed with a levy that prevents the silt migration and the grasslands are now all agriculture mostly Sugar Cane.
you can never stop sedimentation of dams. you can mitigate, but physical removal will always be a necessity
Uh yeah, I think that was the point of the video.
The finest silts make it all the way to the dam and you can see it seeping in through the gaps in the lower galleries.
Silt can also block harbours. Specially older harbours founded in a time when depth was not the primary driver, and storm shelter often was more important. A famous example in Europe is Belgian Bruges, a medieval prosperous town with a harbour. It lost a functional harbour that routed a high percentage of Northern European trade due to silting. Because of that however, the architecture survived and now it is is tourist town. In modern times, even the North Sea is dredged to allow Brazilian iron ore vessels to reach Rotterdam. (these largest class of ships only go to certain Chinese deep sea harbours and Rotterdam)
The speed at which you create quality content is amazing. Take good care of your self.
Our small local dam is empty once every few years. Then they dig out all the soil. Thought that happens everywhere😮
Another first class video. Awesome channel! 😃
The flip side of this situation is the fact that dams increase coastal erosion. The silt and sand that would go to building beaches and marshes is trapped behind the dams and causing problems with them.
@Acceleration Quanta That's not what happened when the dams on the Elwa river in Washington state. The mouth of a river is a long way from the bottom of the ocean.
I would suppose that is why Norwegian Hydro power is so effective. The dams are in the highlands where there is very little soil. There is quite a bit of mineral accumulation that probably does some damage to the turbines. Quite a lot of silica due to the bare mountains I believe.
Not mentioned here is the role of silt in the prevention of coastal erosion. The Amazon dumps around 3 cubic kilometers of silt in to the ocean every year. Prevent that silt from flowing and you change the entire east coast. Recent coastal flooding in Asia for example was made worse by the lack of silt transported in the decades earlier. It has to be said however, that there had been very little done to mitigate the problem of siltation.
Bottom line: We want that silt downriver, not in the dams.
Thanks!
I once camped atop a silted dam for a back country project. We drank filtered water from a pit we dug in the silt. It was the worst water I had ever tasted, full of tannins and who knows what, clogged our filters almost instantly. We were finally relieved by a storm that caused some streams to flow. Now I work at a mine where I see this effect on a fractally small scale on a daily basis.
In Pasadena CA there are two dams that are heavily silted. Both are on the Arroyo Seco. Not a river (only when it rains), but more like it's Spanish name suggests; arroyo: stream/brook. There's the Devil's Gate Dam, it's been dredged for the last few years. Mind you that Southern California doesn't get much rain. During the summer there's hardly any water. Making it easier to haul away all that silt. But when it does rain there is so much silt that comes down the mountain. Then a few miles upstream is the Brown Mountain Dam, built in 1943, according to it's website. It's a rather small dam. The website says that it's 81ft high. If you hike up to the dam now you will see that it's silted all the way to the top.
If you're from the area do yourself a favor and make the hike. There's not much of an elevation gain, I think it's only 500ft over 2 to 3 miles. It's hardly felt.
Thank you for this uncommon type of information about civil engineering.
I appreciate your work in educating your followers on critical pieces of infrastructure - industrial, civil, or otherwise.
Greetings from the UK,
Anthony
One solution would be to have a pre dam dam that lowers the speed of water and is designed to be easy to clean of sediment. But it is expensive and long term
I like that at the beginning of every video there's a map (almost) showing where my home is.
I don't think dredging is that expensive, especially if it's just once per 50 years. You can do it from floating riverboats to reach everywhere in the reservoir bed.
I think the real problem with this stuff is that most dams are the small cheap versions that exist at almost every river, often unregistered and old, and they piled up with crap that made them useless by now. Will take massive re-industrialization effort to go fix up all those.
Silt is really a problem called a loosing battle in the dam.
In my region there is a river with 8 power plants and 2 flood dams. At first nobody really payed attention to silt, but 30 years ago a major drought revealed that there is no storage anymore.
Since then there is constant work on the silt problem, and no matter what they do, they barely maintain the level or maybe advance by little bit year over year. Last estimate was they restored around 5% of the storage capacity.
What about them benifits? A silted dam becomes a piece of flat land with deep and very fertile soil. As for a hydro electricity dam, a silted dam will effectively always be high.
4:31 yeah .. but you know what its really really good for? plowing into unproductive sandy solid to make it more fertile and to plowing into farm land or mixing with green waste for compost (presumable) also maybe the guy from Dubai could suck it up for there land reclamation instead of steal other peoples sand...
Interesting topic. I don't know how accurate the claim is, but allegedly, China's huge 'Three Gorges' dam on the Yangtze river will become silted within ~50 years due the high degree of silt coming from upstream. What's worse is that the silt contains a LOT of pollution.
Have we considered simply exploding the silt?
On a more serious note, I wonder if, keeping this in mind, it would make sense to build dams in pairs, with the expectation that only one would be fully operational at a time. Then, when the one in operation needs to be desilted, the other one can 'take up the slack' by being put into operation.
I mean, there are no silver bullets, but just something that came to mind.
Edit: That's what I get for not waiting until the end of the video!
It is cost-prohibitive to do that though
That would be the price of two damns to effectively only have one
12:17 lol sort of almost one one of thos massive bucket wheel excavators they use in german for lignite coal and then just have it automated to run up and down the side of the lake just constantly digging away lol
Yep, there was a recent job done to prevent silting at the Zengwen reservoir. It also has a connection to another reservoir, I guess it is the Wushantou?
There is a simple, inexpensive fix for this problem that would decrease silting by one or two orders of magnitude (10 to 100 times less). Simply ensure that beavers occupy as much of the catchment of these dams as possible. Their ponds collect the sediment and turn it into valuable 'bottom land'. And they do so much more. They a) reduce flood peaks and increase low water flows, b)direct water underground where it is save from evaporation, c)store much more water than is in the pond itself by raising the water table in the surrounding area, d) greatly increase biodiversity in their area, e) remove nutrients from the water and on and on it goes.
I like how varied your content is, I use to watch your videos about industrial topics, but now I enjoy your videos even though I can’t predict what the next topic is
The fact we know about it and implement nothing to get rid of the problem.
Like why cant we add a door at the bottom or multiple doors that we open 1 or 2 times a year for a short time to get rid of extra dirt behind dam walls.
Every time I see a new video from you it makes the day better
Underrated subject. It won't be as popular, but thanks for doing this.
It will be as popular as his average video
"Dead Storage". I just thought applied to the Hoover Dam and Lake Mead, near Las Vegas. Last year, due to the prolonged drought, they found quite a few dead bodies there. You know Las Vegas & the mob connection.
You can thank California for that one too.
5:40 Years ago the lower Mississippi River had this problem. Someone offered a fix for a low price which would be paid upon completion. They accepted it and he fixed their problem. The same basic solution of rerouting the flow like sweeping with a broom can probably be used here.
Yep, silt fill in reservoirs is a problem everwhere, but regular dredging can mitigate that problem.
This is a major problem in my state (MS) in the US. MS has several large flood control dams and deals with a lot of rain and lots of fine alluvial sediment. It keeps the army corps of engineers here who manage these quite busy.
3:23 check your source. The picture on the left is Tourtemagne Reservoir in Valais, Switzerland, with glacier in the background (Hauenstein 2005)
I spent a summer hiking in the canyons of Utah. I got to see, first hand, the damage silting does to a number of small reservoirs. Take into account that many of the places that are good for dams are not very accessible to heavy machinery. It's a complex problem.
Agriculture has been dealing with the issue of silting for over 100 years in Australia, possiblity many hundreds in other countries, we use smaller settling ponds that catch water and gradually let's it flow into the main reservoir via channels or pipes, the smaller ponds dry up quickly and are easily cleaned in a day or 2 with heavy machinery.
In the case where it is not dry you can transfer the water via diesel pumps.
i would expect a dam to have smaller gates on the bottom that would open for a short period of time once every few years to wash the silt out and then close
Ikr? My mind can’t get over why this is so hard. They got all the energy from the dam they need to do any engineering solution. Huge automatic rotating shovels. Whatever, sheesh. Like 13:10 the romans flushed it out. Wtf is that so hard?!
@@TheBooban yea i mean there is alot of lost technologies from ancient times. like the aztecs and mayans 100% had tech that was lost to the epidemics that killed 90% of them. also the tech the egyptians used to build the pyramids. roman concrete still hasnt been reverse engineered. also "atlantis" and all that stuff noone knows where it went other thaan it probably got wiped out ~12k years ago when the sahara went to desert because of the cycle where it gets lush every 5k years then back to desert 5k years later
@@ghostbirdlary I was just talking about this with a friend. Also, when you realize ancient cities had, in many cases, only 200,000 people, 500,000 people, and it makes you think wow they achieved all these things without needing tens upon hundreds of millions of people.
@@stevens1041 yea except like there was one in south america with an estmated 3 million people i think. and "atlantis" was estimated to be like 1 million
Very cool video, I was not expecting such a subject to be tackled on this channel.
For anyone else who might have been pleasantly surprised by how interesting this video was, I can suggest the channel Practical Engineering. The host Grady offers some very interesting material about everything concerning our constructed environment.
I like Grady’s channel, but I don’t recall a video showing this aspect of water engineering, he focuses on the hardware and physics behind it, not really on the long term consequences. I can’t think of a channel off hand to recommend but I’ve learned many times more about the entire cycle and effects from other sources.
@@rydplrs71 He absolutely could make a similar video about it, just with American examples instead of Chinese/Taiwanese ones ;-)
Hear, hear! Grady rocks, and he calls it like it is. Good call.
Asianometry Another cool topic about silt is how it makes clay! You could do a whole video about clay pottery history in asia, briefly tied in with the composition of clay. Love your videos, keep them coming!
I was just wondering if there would be a market for this type of silt, whether it's good for building, agriculture, etc.
I wonder... I saw one of the dams open spillway and spew tons of mud. What would happen if near the bottom of the dam we would make an optional spillway that opens on a regular basis, but just a thin flat thing, not very big. Open it just enough, so silt goes, close when you see water. Repeat every few days.
With enough level difference, water would fill the hole with new silt, and you should reach some kind of equilibrium state.
especially if currents would be engineered to pass over that thing, and leave all the silt incoming. Anyone knows any issues with that ?
Seems like silt could be useful material for construction.
Finally a video on a topic I find oddly interesting! Great stuff
Elk river Minnesota opens up the dams every several years to drain the lake and dig silt out and put it back in the fields. Usually only takes the summer, but not more than a year.
Excellent job - on-par with Grady @Practical Engineering!
What is the economic value of all the silt, and quit it be used for something?
Hadn’t heard of this before. Now I’ll be waiting for a Practical Engineering video on the topic
temporarily divert the output electricity to giant AI controlled robots that use megawatts of power to remove the silt.
I suggest you take a look at The Loess Plateau and how it has been recovered.
Also, investigate the Paani Foundation's Water Challenge in India.
By Louisville Kentucky they used to have a incline belt for mining gravel out of the river perhaps that could help replenish farm lands if not to polluted
That is absolutely not koorawatha dam on the left, there are no glaciers in australia
Really feeling satisfied that the Palmyreans (lived in central Syria) had achieved something!
Oh yeah that makes sense. Usually during springs our local reservoir opens the gates to let through the copious amounts of water from melting snow, at the same silt gets moved too I assume.
This was very interesting. I know absolutely nothing about dams, nevermind the silting of said dams. With that said, the creator made a video that was still interesting and easy for a layman to follow. Good work all around.
I guess videos about sediment buildup in reservoirs is topic that more people than I had previously assumed would enjoy.
I look forward to every new video. Such a wide range of interesting topics.
Oh I just saw a short video demonstrating this whole video. Someone was showing how a dam works but after putting a sponge into a clear container that had water flowing from left to right, they added in small sedimentary sand after the water levels changed. I wasn’t sure it would be that bad on a larger scale but it looked like it wouldn’t be good even on a scale as big as your hand. First everything slowed down (mind you the initial flow of the water and sand was fast already) then it all slowed down, flooded till it was level, and as he added more sand, it all flushed out and even went faster than before. I feel like it’s a video someone found and just said “this is how a dam works” but I don’t think that was the original purpose of that video now. Wish I had the link from Instagram, I’d post it here.
Build small continuous flow tunnels at the bottom of new dams, with maybe some larger ones that can be open as needed.
We have a major issue with silting on the lower parts of the Columbia River caused by volcanic ash still coming down the tributaries from the 1981 Mt St Helens eruption. They have to hydraulically dredge the river yearly to keep the shipping channel open.
Near Angkor temple in Cambodia, there're 2 large man made reservoir built a thousand year ago: east Baray & west Baray.
The east Baray is 90% filled with sediment while the larger west Baray is not.
Wonder why they don't behave the same way.
West Baray also had issues in monsoon failure 500 years ago.
Either way, artificial irrigation channels eroded downwards forming rivers, and so each tree ring shows varying over / under irrigation.
A small point, but the cost to LA county was not per square meter, but (worse) per cubic meter.
Outlets near the base of the reservoir? Open occasionally to flush silt out?
Older dams never had this designed in..and you would only scour out the silt right up at the dam...
If you had the desilting passages built in at construction...
and a huge armoured flexible pipe with a powered "pool cleaner" at the far end...
you could do far better?
@@JohnSmith-yv6eq I'm a software engineer, just wondering :) thanks for your thoughts. I realize that silt is probably abrasive and no fun for metal pipes.
Using explosives to fix engineering problems is a very American solution. :)
4:11 A cargo ship passes sandbanks near Kabul, Germany during historically low water on the river Rhine.
The chances of getting stabbed in Germany may be similarly high, but the last time I checked Kabul was not in Germany.
well... silicon is silicon. either in nm or mm scales
Some tree huggers would recoil at introducing species that bottom feed. Our drought in the American Southwest is a good opportunity to evaluate such problems. When the waters return, could hydraulic dredging from pontoons onto accompanying pontoons allow water to flow over the 'filling' pontoon and 'that' pontoon be ferried to a location where the silts/soils/gravels be removed to some sort of gravel operation to separate and sent to beneficial uses? Just saying . . .
I had no idea this was a effect, very interesting, good video!
You should read Cadillac Desert. People need to watch the videos about removing the dams on the Elwa River....silt and wood are critical to near shore habitat where the rivers enter the oceans....off river channel storage is probably the best solution.
Yeah! You said something about my country! \o/ (Brazil's Itaipu Dam)
they dredge it out every 10 years here at the hydro plant. drain the forebay, lower in loaders and heavy equipment.
I think the asianometry guy and the Pure Kino guy are secretly the same person. illuminato confirmed