How Do You Measure A Waterfall's Height?

One of the most often-reported parameters about a waterfall is its height.

How often do you see brochures or websites reporting that Angel Falls is the tallest waterfall in the world at 898m (3,292ft), or some waterfall is X times taller than Niagara Falls, or Yosemite Falls is one of North America’s tallest at 2,425ft, etc. etc.?

Indeed, what is it about a waterfall’s height that grabs our attention so much?

Does that number somehow give you an indication of the waterfall’s scale and magnitude without having been there? Do you use that number to determine whether a waterfall is tall enough to be worth visiting?

And it’s not just waterfall lovers who tend to notice waterfall height. Tour operators and tourism authorities have also noticed this. In fact, sometimes liberties have been taken with that number (i.e. they’re usually exaggerated) to entice visitors to come (and spend money) or bring a little more publicity to their attraction.

In this page, we’re going to discuss how you measure the height of a waterfall. But before you wonder why we’re devoting a whole page to something that seems so obvious, realize that you don’t always have safe access to the very top of the waterfall. So what else can you do to get some sense of a waterfalls’ height?

We’ll highlight a few of the ways this can be accomplished (though we saved the best for last).

METHOD 1: THE BRUTE FORCE METHOD

The brute force method is nothing more than going right up to the top of the waterfall then dropping a line with a weight tied to the end of it. You continue dropping the line until the weight touches either the ground or the plunge pool.

You can usually tell when the weight has touched the bottom because the line that you’re holding will lose its tension.

When that happens, you mark on the line (at the top of the falls) so you can measure the distance between your marking and the weight where it’s safer to do so. That distance represents the height of the waterfall.

This method works if you’re measuring a vertically dropping waterfall where the cliff that you perform this measurement from is vertical enough that nothing gets in the way of the weight at the end of the line (except the ground terminating your measurement).

But what happens if you’re trying to measure the vertical height of a cascading waterfall where the waterfall itself is on a slope? Under such circumstances, the weight will prematurely touch the sloping ground and you’re prevented from getting an accurate measurement of the overall height of the waterfall in question.

This highlights the main flaw with this brute force method.

Another major problem primarily has to do with safety. First off, the edge of a waterfall (let alone a cliff) tends to be unstable and could give at any moment. Second, access to the very brink of the waterfall usually isn’t safe and requires off-trail scrambling which accelerates erosion.

Nonetheless, this has been accomplished for some waterfalls. One example that comes to mind was the authors of The Ultimate Kauai Guidebook who managed to measure Wailua Falls using this method.

METHOD 2: QUICK ESTIMATION

I call this the lazy person’s method because it requires nothing more than a reference and a lot of judgment.

Admittedly, this is the method we tend to use since we’re usually on holiday where time is very precious (both from a vacation hours standpoint and from the fact that travel is generally costly).

Unfortunately, it’s very inaccurate. Besides, often times, we only care roughly how tall a waterfall is and leave the accurate measurement to academics.

In any case, the method goes like this.

You basically take an object that happens to be standing next to or near a particular waterfall. If it’s a person, you can estimate that his or her height is about 5 feet. Then you can imagine stacking that person on top of each other a bunch of times to arrive at an estimated height of the waterfall in question.

Similarly, you can take a tree that you might assume to be 30 feet tall, then imagine stacking that tree a bunch of times to arrive at an estimate of the height of the waterfall in question.

As an example, let’s apply this method to say Pe’epe’e Falls, which is pictured here.

In this instance, we have an object (a person in this case) standing near or next to the waterfall, and we’re using that person as a reference. If we assume that the person is about 5 or 6ft tall, then we imagine stacking this person about 10 times to cover the full height of the waterfall.

Therefore, a 5 feet tall person stacked 10 times means Pe’epe’e Falls would be about 50ft tall. Of course, if we assumed that the person was 6ft tall, then the falls would be about 60ft tall.

Just based on the above estimate, you can see there’s already a flaw in the method as our assumption of the height of the reference object could already cause a 10ft difference in the height of a waterfall alone (even more error if we had to stack even more people to cover an even taller waterfall).

Nonetheless, it does provide a fair enough ballpark estimate, and it’s certainly pretty quick to apply despite its inaccuracies.

METHOD 3: CONTOUR LINES OF TOPOGRAPHIC MAPS

This method involves looking at a topographic map, then tracing a watercourse over a waterfall and recording the difference in height from start to finish using the mapping software’s ability to track the elevation difference throughout the trace.

This is one method where you don’t have to be in the field to make a reasonable guess as to the height of a waterfall!

It has been put to extensive use by the folks at the World Waterfall Database (often times debunking certain claims but at the same time possibly giving too much credit to waterfalls that don’t quite stack up to their more famous counterparts).

Below is a screenshot of this principle being put to use within the Topo! California software. Keep in mind that this method may not be possible in all cases as topographic maps are hard to come by in many countries.

In this example, I chose Yosemite Falls. I traced Yosemite Creek from around the top of the falls all the way down to its base. At the bottom of the screen, Topo! was able to build a profile for me and show that the waterfall is roughly 2500ft tall (corroborating the 2425ft claim). However, if this profile feature isn’t available, you’ll have to manually read the contour lines (there are numbers representing elevation for each line) and do the subtraction and judgment call manually.

The big downside to this method (besides the availability of topo maps for the region of interest) is that you don’t have the information gained from being in the field. We’ll get into these complications shortly.

Nonetheless, like the lazy persons method stated above, the topo method is pretty effective in getting a good ballpark estimate of a particular waterfall.

Complications to Waterfall Heights

Indeed, the method for reading topographic maps to determine a waterfall’s height exposes some serious complications that extend beyond the scope of our discussion here. So we’ll summarize these complications here.

First of all, sometimes it’s hard to tell where one waterfall begins and where one ends. This is certainly a critical piece of information that is necessary to better determine a waterfall’s height simply by looking at a topo map, but it typically requires being in the field in order to get that information.

Here are some scenarios where it’s not straightforward to define where a waterfall begins and ends.

Take Norway’s Vedalsfossen for example. Notice how it has a plunge near its top and then a long series of cascades as it makes its way down to the Hjølmo River. Should those cascades count as part of the overall drop of the falls?

For these types of examples, it seems that the Norwegian authorities have a tendency to express waterfall heights in terms of their vertical plunge only.

Thus, you’ll frequently see waterfalls like Vettisfossen be tagged with the tallest singular Norwegian waterfall while we know there are other ones that are taller from a cumulative height standpoint such as Mardalsfossen.

In our opinion, we tend to count those cascades as part of the overall drop, but we’ll also try to note the vertical plunge as well. Usually, we rely more on information in the literature before putting on our BS meter to see if the claims hold up.

In another example of how determining the start and end of a waterfall can be complicated, what happens if you have a waterfall that consists of multiple waterfalls? Where does one begin and where does one end? Or should they all count together as one big cumulative drop?

Take the Giant Stairway (i.e. the Nevada Falls and Vernal Fall combo) for example.

In this instance, the Merced River plunges in two distinct sections each separated by a significant distance if you’re hiking. However, they look more-or-less together when viewed from above in a lookout like Washburn Point or even Glacier Point. So should this count as one big waterfall or two separate ones?

In our opinion, we think they’re two separate waterfalls because they’re far enough apart from each other that it’d be hard to see them together from the ground. Of course, you can already see there are problems with this logic given its subjectivity. Thus, we’re not totally committing to this rule-of-thumb on the subject.

Another example similar to the Giant Stairway is the pair of waterfalls on the Yellowstone River dropping over both the Upper Falls and Lower Falls.

Then, there are examples where we think the multi-drop waterfalls should count as one entity as their respective segments are much closer together than the above examples. Such waterfalls include Yosemite Falls, Belmore Falls, Mitchell Falls, and Gullfoss among others.

A related subject (though not necessarily pertinent to ascertaining the height of a waterfall) is the question of whether a waterfall counts as a single entity or multiple entities when the stream splits.

In other words, how far apart must a waterfall be in order to count as separate entities if they come from a common stream?

Ntumbachushi Falls in Zambia comes to mind in this regard.

METHOD 4: CLINOMETER AND RANGEFINDER COMBO

If I was more academically determined to measure every single waterfall I visited, then this would be by far the best in-the-field method, period!

It basically involves some trigonometry and the use of a couple of handy devices you can buy commercially – a clinometer and a rangefinder.

The basic principle is this.

Through the use of trigonometry (i.e. the relationships between the length and angles in a right triangle), you can determine missing pieces of information simply by determining the length of the hypotenuse (the longest leg) of the triangle and the angle.

Actually, if you know just the angle and the length of any leg of the right triangle or the length of any two legs of the right triangle, you can figure out all the other missing parameters of the right triangle, but I digress.

The drawing below (Figure 1) illustrates this graphically for a situation where you’re at the bottom of a waterfall.

You can get the hypotenuse measurement by using the rangefinder, which tells you how far away something is that you see through the tool.

You can get the angle measurement by using the clinometer, which tells you the angle of our line of sight relative to the horizontal.

Given these measurements (and realizing that the sine of an angle is the ratio between the opposite leg of the triangle and the hypotenuse), the height is determined by the trigonometric formula:

height = hypotenuse * sin(angle)

Now, you also have to add to the height how high your eyes are off the ground (typically around 5ft or so depending on how tall you are). The final formula then becomes:

waterfall_height = hypotenuse * sin(angle) + eye_level

Now let’s look at what happens if you’re at the top of a waterfall (Figure 2)?

Again, you can still use the rangefinder to get the length of the hypotenuse of the right triangle and the clinometer to get the adjacent angle of that triangle.

However, you now have to use a different formula because we’re talking about different legs of the triangle. In this instance, you have to rely on the fact that the cosine of an angle is the ratio between the adjacent leg of the triangle and the hypotenuse.

In other words, use the following trigonometric formula:

height = hypotenuse * cos(angle)

Now, you have to subtract from the height how high your eyes are off the ground because eye level is higher than the top of the waterfall. Thus, you end up with the final formula:

waterfall_height = hypotenuse * cos(angle) – eye_level

Now, what happens if you’re neither at the bottom nor at the top of the waterfall, but somewhere in between (Figure 3)?

Well, this scenario can be solved by dividing up the waterfall in two where you’re eye level is the dividing line.

Let’s first focus on the upper part of the waterfall.

Focusing on an object at the top of the waterfall or the top of the waterfall itself (nontrivial to pull off the latter), use the clinometer to get the angle relative to eye-level and the rangefinder to get the hypotenuse length (just like the bottom-of-the-waterfall approach mentioned earlier).

Then use trigonometry to get the height of the upper part of the waterfall.

This can be described by the following formula:

height1 = hypotenuse1 * sin(angle1)

Now, let’s focus on the lower part of the waterfall.

Focusing on an object at the base of the waterfall or at the bottom of the waterfall itself (nontrivial to pull off the latter), use the clinometer to get the angle relative to eye-level and the rangefinder to get the hypotenuse length (once again applying the bottom-of-the-waterfall approach).

Then use trigonometry to get the height of the lower part of the waterfall.

In mathematical terms:

height2 = hypotenuse2 * sin(angle2)

To get back the waterfall’s height, add the two results:

waterfall_height = height1 + height2

Another way to think about this calculation is that you’ve got two right triangles back-to-back with each other sharing their horizontal leg (which happens to be eye level). Thus, you’re applying the you’re-at-the-bottom-of-the-waterfall calculation twice (where the bottom triangle is simply flipped about the eye-level axis).

There’s still yet a fourth case that is quite common: you’re standing at a spot that’s higher than the top of the waterfall (Figure 4).

Once again, you take two angle and hypotenuse measurements with the clinometer and rangefinder, respectively.

Take the first angle and hypotenuse measurements by focusing at the bottom of the waterfall or some nearby object at the same level. Plug in your measurements into the following formula to get the height between your eye level and the base of the waterfall.

height1 = hypotenuse1 * sin(angle1)

Now take the second angle and hypotenuse measurements by focusing at the top of the waterfall or some nearby object at the same level. Plug in your measurements into the following formula to get the height between your eye level and the top of the waterfall.

height2 = hypotenuse2 * sin(angle2)

To get the desired waterfall height, perform the following subtraction:

waterfall_height = height1 – height2

Finally, there is a fifth scenario, which is what happens when you’re standing way below a waterfall yet you’re still able to see both the bottom and top of the waterfall.

Under this circumstance, you’d still take the same measurements as above. That is, height1 would be the height between where your eyes are and the bottom of the waterfall. Meanwhile, height2 would be the height between where your eyes are and the top of the waterfall.

Then, to get the desired answer, you’d perform the following subtraction:

waterfall_height = height2 – height1

Indeed, the beauty of this best-in-the-field method is that you can apply these methods to almost any situation.

It doesn’t matter whether the waterfall is sloped or tiered, because you only care about the overall vertical drop.

Plus, you’re only limited by how far the clinometer and rangefinder can see.

In other words, you can measure the height of a waterfall that’s far away just so long as it’s within the range of the measuring tools – the rangefinder and clinometer.

CONCLUSION

So you see, the question of how tall a waterfall is can be a surprisingly complicated subject.

And while you’ll no doubt continue to see various claims about how tall a waterfall is (usually taller than the reality might be), numbers alone can’t replace the beauty, benefits, and variety that waterfalls bring in general. Besides, we usually have our BS meter on and see how the numbers stack up to our gut feeling after seeing it in person.

Even though we may glance at a waterfall’s reported height when we know little else about that waterfall during the course of our travel research, we generally care more about how we would react to it (especially after seeing it in person) than the statistics.

In the end, it’s really about what waterfalls do for you rather than how they statistically stack up.

This is why our Top 10 Waterfalls List doesn’t necessarily take into account a waterfalls’ height.

Sure there may be taller ones out there we’ve personally visited that didn’t make the list, but in our minds, the Top 10 waterfalls are the ones that exemplify the best of the best all around irrespective of academic trivia.