The Hidden Engineering of Niagara Falls

0:01 Niagara Falls is one of the most spectacular waterfalls in the world.

0:05 With a vertical drop of more than 50 meters or 164 feet and a flow

0:11 rate that often exceeds 2800 cubic meters

0:14 per second or 100,000 cubic feet per second,

0:17 it’s one of North America’s crown jewels.

0:20 Roughly ten million people visit the falls every

0:23 year just to catch a glimpse of the curtains

0:26 of water pouring over the edge and the constant clouds of mist at the bottom.

0:31 But Niagara Falls isn’t just a tourist attraction.

0:34 The special geology and hydrology of this region,

0:38 situated between Lake Erie and Lake Ontario,

0:41 have resulted in some fascinating feats of infrastructure,

0:45 from shipping to electricity to water control.

0:47 It’s basically a microcosm of all the things I love.

0:51 The falls themselves have required quite a bit of engineering over the years,

0:56 and they’ve even been shut off for maintenance.

0:59 Let’s take a little tour of the Niagara

1:01 Peninsula (even though it’s really an isthmus),

1:03 and I’ll show you some of the things that aren’t usually listed in a guidebook.

1:07 I’m Grady, and this is Practical Engineering.

1:21 Let’s get oriented first.

1:23 This is a map of the isthmus.

1:25 We’ve got Lake Erie to the south, Lake Ontario to the north,

1:29 Buffalo and western New York to the East, and Ontario, Canada, to the west.

1:34 The Niagara River runs northward, connecting the two great lakes.

1:38 And right in the middle,

1:40 it plunges off the Niagara Escarpment, creating the famous falls.

1:44 On the US side, there are the American Falls and the smaller Bridal Veil Falls.

1:49 And on the Canadian side is the Horseshoe

1:51 Falls where a majority of the river flows.

1:54 It’s pretty impressive to see in person,

1:56 but it’s actually not entirely a benefit.

1:59 Because these falls pose a major problem for shipping.

2:02 The Great Lakes form the largest

2:04 inland freshwater transportation system in the world.

2:07 Since the 19th century, they’ve served as the backbone for moving iron ore,

2:13 coal, grain, and manufactured goods between

2:15 the American heartland and the Atlantic Ocean.

2:18 Ore from Minnesota and grain from the Midwest can travel by ship

2:22 all the way to steel mills or export terminals on the East Coast.

2:26 Barges and freighters are efficient at moving bulk

2:29 cargo in a way rail and trucks can’t match.

2:32 For a time, the Niagara Escarpment was

2:35 a natural bottleneck between Lake Erie and Lake Ontario,

2:38 preventing goods from moving directly between the upper lakes and the Atlantic.

2:42 Freight had to be offloaded and portaged around

2:45 the falls before it could continue its journey.

2:48 The Erie Canal solved the problem somewhat,

2:50 starting in 1825, bypassing Lake Ontario.

2:53 But it could only accommodate smaller vessels,

2:56 and even before the Canal opened, another solution was being planned.

3:01 The Welland Canal runs through the peninsula west of the Niagara River,

3:05 connecting two massive areas by shipping traffic for the first time in 1829.

3:10 The canal fueled the early growth of cities along the Great Lakes and St.

3:15 Lawrence River- including Cleveland,

3:16 Detroit, Milwaukee, Chicago, Toronto, Montreal,

3:18 and Quebec City- and it’s been rebuilt and moved several times over its life.

3:25 The Welland Canal is really a titanic engineering achievement and, were it

3:29 not positioned next to one of the natural wonders of the world,

3:32 it would probably be famous in its own right.

3:35 Because of the huge difference in elevation

3:37 between the two lakes created by the escarpment,

3:39 eight separate locks are required to allow ships to traverse between them.

3:44 And all different kinds do- from personal leisure

3:47 craft to the lakers that stay in fresh

3:50 water to the salties that travel between the lakes and the ocean through the St.

3:55 Lawrence Seaway.

3:55 Starting on the upstream, Lake Erie side of the canal,

3:58 the first lock isn’t really for lifting

4:00 or lowering ships so much as for control.

4:03 The level of Lake Erie actually fluctuates throughout the year,

4:06 and there are longer-term trends as well.

4:09 Wind storms also raise the level locally similar

4:12 to the way storm surge works during hurricanes.

4:14 The control lock does just that: it controls the level in the downstream canal.

4:19 It prevents excess water from rushing down the canal when the lake is high,

4:23 kind of like an airlock on a spaceship keeps air

4:26 from rushing out when astronauts step outside for a spacewalk.

4:30 Downstream of the control lock, the canal splits in two.

4:33 The original pathway of the canal flows through the eponymous town of Welland,

4:37 while the larger and newer section of canal,

4:40 the Welland Bypass… well, it bypasses Welland to the east.

4:44 If you look carefully, you’ll also notice a small river,

4:48 the Welland River, which passes underneath both the original and bypass canals.

4:52 On the way downstream from Lake Erie to Lake Ontario,

4:55 shipping traffic passes over aqueducts that pass over a natural river.

5:00 A hydrological wonderland!

5:02 Continuing downstream from the aqueducts,

5:04 the remaining seven locks are lift locks,

5:06 more like what you think of when you imagine a lock.

5:09 Notice how they’re clustered tightly around the terrain

5:12 and not distributed evenly along the length of the canal.

5:15 That’s the Niagara escarpment,

5:17 the same geological feature that the water cascades down at the falls.

5:21 This is the elevation diagram of the entire Great Lakes and St.

5:25 Lawrence Seaway system from Lake Superior to the Atlantic Ocean,

5:29 and you can see that this drop is the biggest one of the whole thing.

5:33 And that’s pretty important for another

5:35 part of the infrastructure on the peninsula.

5:38 The power available from a moving fluid is directly proportional

5:42 to the flow rate multiplied by the height of the drop.

5:46 In most hydropower applications, that height is created artificially by a dam.

5:50 There aren’t that many places in the world where you have both

5:54 a large volume of flowing water and a significant natural drop in elevation.

5:59 But that combination made Niagara Falls the birthplace

6:02 of large-scale electric power in North America.

6:07 In 1895, the Niagara Power Company opened the Edward Dean Adams Power Plant,

6:13 built with Westinghouse AC generators based

6:15 on the ideas and patents of Nikola Tesla.

6:18 The plant served as the basis for the modern electrical grids we have today,

6:22 and many of the fundamental concepts are basically unchanged.

6:26 But the power infrastructure at Niagara Falls definitely has changed.

6:30 Where the Adams Power Plant put out about 40 megawatts of power in 1895,

6:35 now the combined capacity from the region is in the neighborhood of 5 gigawatts.

6:40 But in both cases, it wasn’t as simple

6:42 as putting a turbine at the base of the falls.

6:45 While it might be technically possible to generate power by placing a water

6:49 wheel directly in the stream of a waterfall like a kid’s bath toy,

6:52 it’s not the most efficient way (plus it would take away from the beauty).

6:56 The water used to power the hydroelectric plants on both the US and Canadian

7:01 sides of the Niagara River is water that never actually flows over the falls.

7:06 Instead, it’s diverted into five massive tunnels- two

7:09 on the US side and three on the Canadian side.

7:12 Like most tunnels, you can’t really see

7:14 the extent of the hydro tunnels at Niagara Falls.

7:17 There are a few conspicuous clues though, like these gigantic buildings.

7:22 These interesting protrusions from the landscape house enormous steel doors,

7:27 nearly 60 feet tall, that can drop down into the tunnels

7:31 and close off the flow for inspections and maintenance.

7:34 Both the Ontario and New York sides of the river feature similar structures.

7:38 From the tunnels, water flows into major

7:41 hydropower plants on both sides of the border:

7:44 the twin Adam Beck stations on the Canadian

7:46 side and Robert Moses station on the US side.

7:49 Then it’s released into the the lower part of the river below the falls.

7:53 When you add them up,

7:54 that’s 39 turbines with a combined capacity of more than 4000 megawatts.

8:00 It’s a tremendous amount of power generation in one place.

8:03 But actually, that’s not all of it.

8:06 These tunnels divert 50-75% of the flow of the Niagara River.

8:10 That wide range in percentage of diversion isn’t

8:13 because we don’t know how much is diverted,

8:16 but because we actually control how much water is diverted,

8:19 depending on the tourist requirements agreed upon in a treaty by both nations.

8:24 During the day in peak tourist season,

8:26 more water is allowed to flow over the falls to ensure the grandeur of the falls

8:31 is on full display for the huge crowds of tourists that visit every year.

8:35 At night and during the winter, more of the flow is diverted to generate power.

8:40 That’s all managed by this structure upstream of the falls:

8:44 the international control dam.

8:46 I’ve always thought this is an interesting dam,

8:47 since it doesn’t even go all the way across the river.

8:50 But it doesn’t need to.

8:52 This structure’s not meant to create a reservoir;

8:54 it just subtly adjusts the level in the river to control

8:58 how much water flows over the falls versus into the hydropower intakes.

9:02 The US side of the Niagara River is pretty shallow,

9:05 so that side acts kind of like an uncontrolled spillway.

9:08 Then, the gates on the Canadian side can be adjusted

9:11 to balance the competing demands on water between tourism and power.

9:16 But there’s one big problem with those competing needs:

9:19 they both have the same timing.

9:21 We want thunderous cascades of water over

9:23 the falls during the day when tourists are visiting,

9:26 but daytime is also when the demand for electricity is highest.

9:30 It’s like if solar panels only worked at night.

9:33 To accommodate this, both the US and Canada have pumped storage plants.

9:38 At night, excess electricity is used to pump diverted water into reservoirs,

9:44 essentially storing both the power and the extra

9:47 water that’s available during off-peak hours.

9:49 Then, during the day,

9:51 the water is released back into the forebay of the power plants.

9:54 You get a little extra power from that drop

9:57 out of the reservoir into the forebays,

9:59 so both sides have small hydropower facilities to capture that.

10:02 But more importantly, you get a lot more water during the day than

10:07 would otherwise be available to run through the big plants,

10:10 making more power when it’s needed most.

10:12 And there’s just something funny to me that the infrastructure

10:16 is duplicated on both sides of the river,

10:18 like neither country was willing to be one-upped by the other.

10:22 All of this diversion noticeably reduces the flow of water over the falls.

10:26 Even when they are at ‘full blast’ during the day in the tourist season,

10:30 only 50% of the flow of the Niagara River makes it over the falls.

10:34 You can imagine how powerful the falls would be

10:37 if 100% of the flow were to cascade over.

10:40 It might seem like this diversion detracts from the majesty of the falls,

10:44 but in another sense, it actually preserves it.

10:47 All waterfalls undergo some degree of erosion as the water

10:51 and sediment suspended in it scours away the rocks and soil underneath.

10:55 Without any diversion, Niagara Falls would be receding towards Lake Erie

10:59 at a rate of about 3 feet every year.

11:02 At the end of the last ice age,

11:04 the falls were right at the edge of the Niagara Escarpment,

11:07 but thousands of years of erosion have caused them to work their way upstream.

11:11 You can actually see how far it’s

11:13 already progressed by looking at this elevation map.

11:16 Over the last 12,000 years or so,

11:18 the falls have migrated by erosion to their current location.

11:22 By diverting a significant portion of the flow,

11:25 the power plants have actually slowed the rate

11:27 of erosion to approximately one foot per year,

11:30 which will help preserve the falls for a longer period.

11:33 While flow on the falls is downregulated by diversion for hydropower,

11:37 the falls are never ‘turned off’...except for the one time in the 1960s.

11:42 The smaller American Falls (and nearby Bridal Veil

11:45 Falls) have a pile of loose rocks and boulders, called talus, at their base.

11:50 This pile of rocky debris actually extends

11:52 a good fraction of the way up the falls,

11:54 and officials worried that the falls might ultimately transition into a series

11:59 of rapids cascading down the slope

12:01 of talus rather than remaining a majestic waterfall.

12:05 So, in 1969, the Army Corps of Engineers built

12:08 a temporary cofferdam between the New York shoreline and Goat Island,

12:12 diverting the water over the Canadian Horseshoe

12:15 Falls and leaving the American Falls dry(ish)!

12:18 After the engineers got a chance to inspect the situation,

12:21 they determined that the best course of action was

12:24 just to leave the majority of the talus in place,

12:27 since it seemed to be stabilizing the cliff face.

12:30 Sometimes, doing mostly nothing is a decision you make as an engineer,

12:34 even if you have to do a monumental amount of work to come to that conclusion.

12:39 So the cofferdam was taken out,

12:41 and water has flowed continuously over all the falls since then.

12:45 It really highlights the complexity of Niagara Falls.

12:48 On the one hand, you have one of the natural wonders of the world,

12:53 an absolutely enormous set of waterfalls that inspire awe and wonder

12:57 in the countless travelers who are lucky enough to take in the view.

13:01 The same thing that makes it impressive for tourists (the big

13:04 drop) makes it valuable for power and a major challenge for shipping.

13:09 And out of that comes all kinds of fascinating infrastructure,

13:13 not only to facilitate the tourism but the other stuff too:

13:17 a major canal with locks and aqueducts, the international dam control gates,

13:22 pumped storage reservoirs, epic tunnels, towering gates,

13:26 massive hydropower plants, and so much more.

13:29 It’s really a pretty remarkable place for engineering.

13:33 My wife and I actually visited the falls back in 2018,

13:37 and even crossed the Rainbow Bridge to the Canadian side for coffee with a view.

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