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"This is how to make a river disappear." It's been done with rivers all over the world, likely where you live, too. "You've probably walked over them without even knowing it. Just like me right now." Today, cities are spending millions to dig them back up. But why? And how do you even unbury a river? To find out, we've come to a city that was once part of England's industrial heartland. Below Sheffield, there are many buried rivers. We're going underground to explore them and understand why they were even covered up in the first place.
"Hello!" "Julia?" "Yes!" "Anthony." "Nice to meet you. Hello!" "So, you're ready?" This is Anthony Wood. He takes people on tours in Sheffield's culverts. They are the tunnels built to hide the city's rivers. The tours are organized by a local charity, the Sheaf and Porter Rivers Trust, which works to protect and restore the city's rivers. Its chair, Simon Ogden, is coming along on the tour, and we'll hear more from him later. "So, yeah. We're about to enter underneath the train station."
"Dark and tiny spaces are really not my comfort zone but we'll see." "It's all cool, don't worry. How are you with spiders?" "Fine." Well, we'll see about that. We're lucky there hasn't been much rain recently, so the water level is low. After heavy rain, tours like this often have to be called off. "Just watch your feet around here because there is." "How does it end up here? It just happens because people throw stuff in the river?"
"Yep, exactly." "What is it?" "It's not a PC but…" "Not a DJ set but something with sound, no?" "Yeah. It is a bit of a mystery but probably something that was very expensive at one point. We do find these interesting little mysteries occasionally." "What type of material is that? Like what is it built with?" "So you're looking at a variety of different materials. And it depends on the time the different elements were built. So, this was originally built in the late 1860s, around 1870 because the train station itself was opened in 1872.
So you've got these big stones that were part of that." Over the years, more stones, bricks and later concrete were added bit by bit. "So, you're ready? Let's test your claustrophobia!" "Yes, I guess so." "You see the spiders on the roof all around you?" "Ohhh my… Oh okay, I don't like…" "But you said you were good with spiders?"
"Yeah, but I don't like them that much." Rivers were key to Sheffield's industrial success. Together with the city's hills, they were perfect for water power. This drove the city's most important industries: first cutlery and later steel. "If rivers are so important to a city, why did they bury them?" "At the time the rivers were basically open sewers. So, they had been abused and abused horribly. Literally hundreds of people died as a result of the water being so polluted."
London had the same problem - and it got so bad it became known as the "Great Stink". This is a satirical cartoon from that time. But rivers didn't just disappear in England. New York, Vienna, Moscow, Seoul - cities all over the world buried them too. Sometimes because the water was polluted, but also to make space for the cities to grow. In some cases, the buried rivers became part of these cities' first sewage systems. You can put rivers in pipes, box-shaped tunnels or an arch structure like the one we are in right now. Down here, you can still see how the arches were built.
"So you put a wooden arch over it, you build a frame, and once you have the frame, you can build the actual stones over it. Because the arch is one of the strongest forms you can get. So that was supporting the wooden frame that they built the arch over." In Sheffield, rivers were covered in stages from the 1860s up until the 1910s. It's hard to say exactly how many culverts there are across the city because many cannot be accessed. But this map gives a rough idea. These are the parts of the rivers that flow underground - it only shows culverted sections longer than 50 meters. And all of these are streams that appear on historical maps but have no visible trace today, so we don't know what happened to them.
This is the river Sheaf and this is where it is covered. "Welcome to the Sheaf. When we got to here, we stepped into the Sheaf. So that's the end of the Porter and the confluence with the Sheaf." While the Sheaf and the Porter Brook are covered a lot, the Don is open and flowing right through the city. "The Don is a lot harder to culvert. It's a lot more expensive because it's so much wider and so much bigger and so much more of a change in flow." And underground rivers don't make great homes for fish or plants. "Plant-wise you basically eliminate everything. Unless you have a bit of daylight, you're not gonna have any plants. In terms of the fish, for the most part it's not good for them.
They need daylight, they need the light for the plants, to have the insects, it's a whole ecosystem that relies on itself." It can also hit fish populations if they cannot pass through such structures to reach their breeding grounds. And there is one more problem, and it's quite a big one. Tunnels can only take a limited amount of water. We'll see what that means later. "So, did you enjoy that, now that you're back to safety?"
"Yeah, it was fine, but I am also relieved. Ok, so let's leave the past behind, and let's go look at where Sheffield is actually removing such structures right now." We are in the center of Sheffield, right where the city was founded. Here, the city is opening up a section of the river Sheaf. This is called "daylighting" or - more technically - "de-culverting". But before we can visit the construction site, I have to elevate my outfit.
"And then.super heavy shoes actually but they're here to protect my feet, so I take it." We are meeting Simon Ogden again. He has spent decades working with Sheffield's rivers. He used to work with the City Council and has been involved in this project as well as earlier ones. "Why did the city decide to open up that part of the river?" "So Sheffield is named after the river Sheaf. And yet, the river was almost invisible for maybe about 150 years. So, when the opportunity came to create a park here,
it seemed an obvious thing to do to open up the Sheaf Field. But there are lots of other reasons as well: climate change. With so much more extreme weather, it is a bad idea to have rivers in tunnels. Because the tunnels are like a pipe. When the pipe gets full, the water will go somewhere else. And the somewhere else is people's streets and houses, schools and stations. So, we need to create more room for the river. And also slow the river down as well because when water goes through a pipe, it goes very fast." "And why was that part of the river even buried in the first place?"
"Because the river was so polluted. Where we are standing now was the slaughterhouses for the town. So anything that they couldn't sell from the animals, blood, s**t, bones, was thrown into the river. The river was seen as being a health hazard." This "health hazard" is now open again, and I can confirm it isn't one anymore. But opening it wasn't easy. They had to do it bit by bit. Literally cutting the ground from underneath their feet. To understand more about how all of this works, we are meeting Dylan Rayen.
He is an engineer working on the project. "What are these yellow thingies here for?" "The yellow elements are hydraulic jacks. Where we are stood right now is all soil and all of that is bearing onto these walls and trying to push it inwards. So, the lid of the culvert which we have now taken off initially would hold those walls in place. So, since we have taken them off now, we need to replace that function and here, we've used these temporary hydraulic jacks that we can actually use to exert a pushing force and keep those walls in place." Eventually, permanent structures will do that job instead.
"Wow, that looks crazy! Let's go into the river." These are part of the stabilizing structure that will keep the walls in place once the hydraulic jacks come out. There will be two of these stacked on top of each other against each wall. Then these U-shaped elements are put in the middle and get filled with concrete. This is what it'll look like when it's done. But there's one thing I don't quite understand yet. "This being a river, I don't see much water to be honest."
Back on top, Dylan explains why. "So, some of the solutions that we've come up with to support the existing culvert walls need us to actually access the riverbed, put in some structural elements down there. So it's important that we take whatever measures we can to make sure that the waterbed is safe for access. To do that, we put a dam just in front over here, where we are able to collect the water and send it down the pipe. That allows the river to still maintain its flow into the connecting river Don while the workers have safe access to carry out the works."
Even with all this in place, the river doesn't always cooperate. A few weeks before our visit, work had to stop completely because this is what it looked like. There is still a lot to do: putting in the stabilizing structures, building a way for fish to get through and creating the stairs so people can get close to the river. The original budget for the entire project, including a park, was around £20 million. It was supposed to open in 2026. But costs are expected to be more than a third higher, and the project is postponed to summer 2028.
The money comes from a public fund. In an interview with the BBC, critics said that the Council could have done a better job at planning to avoid delays. The Council says everything is late and costs more because the project is more complex than they expected. But this is not the first river getting dug up again in Sheffield. "So, we're here at Matilda Street where part of the river Porter Brook has actually already been daylighted along with creating a little park." And all of this used to be a car park.
Just like this one. We are meeting Tom Wild here. He studies river ecosystems in cities. "So, what would you say are the biggest benefits of daylighting rivers?" "Mainly really flood prevention, reducing pollution and bringing nature back into the city. Because often these systems of the past, maybe from centuries ago, the capacity of the pipes for instance is too small. And so under heavy flow conditions with climate change, heavy rainfall or flashier flows, the rivers tend to block up these pipes. So, opening them up is a flood solution."
Culvert collapse occured Monday afternoon in Coolville, Ohio. And this is what can happen when there's too much water flowing through a culvert. So, opening them up reduces that risk and might save money in the long run. Open water does something else, too: it cools the city. Which is especially important as cities tend to trap heat and have to find ways to deal with hotter summers in the future. But there are other reasons for daylighting rivers as well. In Utrecht, a canal was removed to create a highway in 1970. In 2002 citizens voted to bring the canal back. They ended up with a greener city, with more space for plants and animals - and bicycles.
Check out our video where we visited Utrecht to take a closer look. A pioneer in daylighting streams is Zurich. They started decades ago and have since opened more than 15km of streams around the city. And it actually saved them money because it improved their sewage system. This spot in Seoul used to look like this. In the early 2000s, the city uncovered the buried river. The structure had become unsafe, and they wanted to revive the area. It worked. But there has also been criticism, saying the restored river was too artificial and that it promoted gentrification in the area. So, why isn't every city doing this?
"Firstly, the cost can be more significant because of existing infrastructure and services." There could be a busy road on top of the hidden river for example. And the land might also not belong to the city - but to a private owner. And that makes things more difficult. "So, we can look at that balance of how much it is going to cost to invest but also in the longer term how does that change the overall let's say sustainability and resilience of those places." In Sheffield, history was important too. The city began right here and gets its name from the river Sheaf. No Sheaf, no "Sheaf Field". But there will always be some places where daylighting is not really an option.
By the way: if you're ever in Sheffield: a few years ago, this was installed as a reminder of the hidden rivers and also to let some light in to help fish pass. "And it's actually quite impossible to open it up here." "Do you know of any hidden rivers where you live? Let us know in the comments below, subscribe for more videos like this and check out dw.com."
