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
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.
@@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.
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.
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.
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.
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.
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.
@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!
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
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.
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.
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.
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?
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.
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.
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.
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.
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
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!
"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.
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.
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 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.
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!
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.
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.
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
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!
Excellent topic/episode. Only one feedback: it's Paraná River Notice the accented a. Pronounced pa.ra.naaah Edit: correct spelling is Itaipú Dam. Now you know how it's pronounced. 😊
Now, tell that to councilors in your local area. They look at you with a blank face. And then the reservoirs get less and less capacity over the decades, I guess it's some one else's problem cause I wont be around when it's a problem. Total face palm.
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.
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...
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.
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
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.
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 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.
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.
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.
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 ?
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)
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.
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.
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.
Dude I'm not gonna pay stop hassling me, just get a real jobby so you can pay your bills, tired of every channel bumming me to support their lazy lifestyle....
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.
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.
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?
@@alcubz2622 Religious authorities are crushing peoples liberties, people protest it but since the government gets something like 90% of their revenue from state owned oil companies and the country isnt a democracy the protests are largely ignored. So basically just business as usual for the Gulf states.
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
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.
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
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?
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.
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.
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.
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.
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.
@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
Your videos are the equivalent of a 3am Wikipedia deep dive about a random yet highly interesting topic.
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
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.
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.
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.
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.
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?
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.
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.
Another first class video. Awesome channel! 😃
2:30 Why say 2000+ milimeters when you could just say 2 meters? Lame attempt to make it sound worse than it was when it was already really bad.
Also, don't forget to spell it correctly. Metre Tonne and Kilometre.
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.
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.
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
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"
"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.
Our small local dam is empty once every few years. Then they dig out all the soil. Thought that happens everywhere😮
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.
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.
Practical Engineering has a very different presentation style than I remember (j/k nice 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.
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
Gotta dig it out. Can't be a lazy stoner.
What is the economic value of all the silt, and quit it be used for something?
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.
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.
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
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.
Isn't silt an insanely good resource?
How is there no economic interest?
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 grrrreat video. thank you for all the work, and then sharing.
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
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.
Excellent topic/episode.
Only one feedback: it's Paraná River Notice the accented a. Pronounced pa.ra.naaah
Edit: correct spelling is Itaipú Dam. Now you know how it's pronounced. 😊
Dams may provide renewable-resource services (water storage, flood control, hydroelectricity), but dam SITES are not a renewable resource.
Now, tell that to councilors in your local area. They look at you with a blank face. And then the reservoirs get less and less capacity over the decades, I guess it's some one else's problem cause I wont be around when it's a problem. Total face palm.
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.
Janos Silt: I HAVE SEDIMENTS! POWERFUL SEDIMENTS!
I guess videos about sediment buildup in reservoirs is topic that more people than I had previously assumed would enjoy.
well... silicon is silicon. either in nm or mm scales
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...
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.
Yeah! You said something about my country! \o/ (Brazil's Itaipu Dam)
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
Underrated subject. It won't be as popular, but thanks for doing this.
It will be as popular as his average video
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.
temporarily divert the output electricity to giant AI controlled robots that use megawatts of power to remove the silt.
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 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.
China seems to be run by dam engineers. Is silting contributing to their trouble with flooding before the current dry year?
Really feeling satisfied that the Palmyreans (lived in central Syria) had achieved something!
I like that at the beginning of every video there's a map (almost) showing where my home is.
I think the asianometry guy and the Pure Kino guy are secretly the same person. illuminato confirmed
Hadn’t heard of this before. Now I’ll be waiting for a Practical Engineering video on the topic
Using explosives to fix engineering problems is a very American solution. :)
Lol I did not know this was even a thing. I’m just sad the fishies can’t get upstream anymore.
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.
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.
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 ?
Dam good explanation of the life of reservoirs (pardon the pun)
You want to watch something amazing, watch his convenient store video!
Seeing that thumbnail i misread it at first glance as "when shit fills your water resevoir"
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)
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.
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.
Excellent job - on-par with Grady @Practical Engineering!
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.
Seems like silt could be useful material for construction.
Yep, silt fill in reservoirs is a problem everwhere, but regular dredging can mitigate that problem.
Cool video. I wonder what caused your interest in this one.
That is some obscure knowledge to impress your buddies at a drinking session!
I love this channel, so interesting.
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 had no idea this was a effect, very interesting, good video!
Please do a video in Japanese industrial spies and their role in the Japanese economy, it's an interesting topic that doesn't get enough attention
Dude I'm not gonna pay stop hassling me, just get a real jobby so you can pay your bills, tired of every channel bumming me to support their lazy lifestyle....
Thanks very educational.
Fiiirst
Feels like Practical Engineering is taking over Asionometry :)
Most of it is impractical engineering.
Silt Happens
_Forrest Gump
Honestly silt doesn't sound as interesting but you made it. Well done man.
Dam, this is interesting.
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.
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.
Nature's solution is the beaver
Haha "how I imagine it happens" 😂
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?
Can you use silt for concrete?
Still waiting to hear your insights on Iran.
Whats up with Iran?
@@alcubz2622 Religious authorities are crushing peoples liberties, people protest it but since the government gets something like 90% of their revenue from state owned oil companies and the country isnt a democracy the protests are largely ignored. So basically just business as usual for the Gulf states.