We know waterfalls.

About our Rating System

Perhaps the most difficult task when it comes to cataloging waterfalls is how to fairly quantify and compare any given waterfall with another. There have been many attempts over the years at creating systems which would effectively rate waterfalls based on their aesthetics, accessibility, volume, quaintness, or whatever else characteristic could be identified.

We have debated for years how to effectively and fairly quantify the many waterfalls around the world. Our previous efforts on this website consisted of using two preconceived metrics, both of which have strong biases towards certain features or characteristics of a waterfall but neither of which were completely foolproof. We then added in our own system of rating the aesthetics of a given waterfall based on our perceptions. While the results of that effort were partially successful, the system was heavily flawed and we have discontinued its use because it relied heavily on our subjectivity and our ultimate goal is to provide a rating as free of bias as possible for these waterfalls.

Whether we have put an end to this issue once and for all will remain to be seen, but we have developed a system of rating Waterfalls which we feel is about as objective as possible. The system uses three primary sources of data and is constructed as follows:

Visual Magnitude

In the 3rd Edition of “Waterfall Lover’s Guide to the Pacific Northwest“, Greg Plumb adopted a system to measure the visual impact of a waterfall which he termed Visual Magnitude. This system uses a logarithmic scale of 10, based on the waterfall’s height, width, volume and slope. The resulting figures render a decent method of comparison between any two waterfalls, despite any and all differences in size or volume. Each increase of 10 in magnitude indicates a doubling of the impressiveness of the waterfall. For example, a waterfall with a rating of 90 is twice as impressive as a rating of 80, and a rating of 100 is four times as impressive as a rating of 80. Taller waterfalls, and waterfalls with a higher volume will have a higher Magnitude rating. Low volume waterfalls, or waterfalls with a shallow slope, on the other hand, have a lower rating because they don’t have as much force. This is the first figure displayed in the Ratings box at the top right of each entry in the database.

We additionally use a metric we call “Absolute Magnitude”, which is the same formula but extrapolated using the highest recorded streamflow data that is available for a given waterfall. This allows us to illustrate the difference in Magnitude of a waterfall between its average flow and flood stage or peak snow melt season flow. This figure is the second displayed in the Ratings box at the top right of each entry in the database, but it is not used in calculating the overall rating of the waterfall.

International Waterfall Classification System (IWC)

A second method of measure that is used in this database is one coined by Richard Beisel Jr in 2002. This system uses a natural logarithm of the average volume of water present in a waterfall to come up with a rating on a 1-10 scale, then rounds it up to the nearest whole number to achieve the class the waterfall falls into. The IWC Rating is listed first, followed by the Class category the waterfall is assigned to, within parenthesis (for example: 4.35 (Class 5) ). This system rewards high-volume waterfalls, and waterfalls with a shallower slope over more vertical waterfalls, because there is more square acreage to low-gradient waterfalls and hence more volume in the waterfall, and is best used to compare waterfalls based on volume rather than height or stature. This is the third figure displayed in the Ratings box at the top right of each entry in the database. As an editorial after note, we find this system to be largely flawed because it awards too little influence to perceived impact and too much influence to run and hence will skew favorably towards rapids and cascades over vertical waterfalls.

The World Waterfall Database Rating System

In attempting to identify a fair way to rate waterfalls against one another, it was determined that both these systems have shortcomings in certain areas and excel in others. To solve that issue, the World Waterfall Database Rating System was developed. It uses both of the above ratings as a weighted percentage of a final score, as well as four additional variables, then grades the final score on a curve based on the highest and lowest possible scores. This allows a 1-100 point system to be employed, and breaks down as follows:

Magnitude – Max 50 Points
A waterfall’s Magnitude accounts for half of its rating. The maximum number of points awarded are reached with a Magnitude of 90.

International Waterfall Classification – Max 10 Points
The IWCR rating, because of its flawed weight of the square acrage of a waterfall and its heavy favoritism towards shallow-sloped waterfalls only accounts for one-tenth of the total. This figure is ported directly into the final formula and few waterfall achieve full points in this category.

Visibility – Max 10 Points
How easily a waterfall is viewed accounts for up to 10% of its final score. More points are awarded for fewer visual obstructions when viewing the waterfall. The number of viewing areas doesn’t weigh on the scoring, but if multiple viewing areas are available, the score will almost always be higher as a result. If easily accessible viewpoints are obstructed but hard to reach viewpoints are unobstructed, the score will reflect the least obstructed viewpoint.

Surrounding Development – Max 10 Points
This allows us to take into account Man’s influence on a waterfall and its immediate surroundings. Waterfalls in their untouched, pristine natural surroundings will receive full points, whereas waterfalls located in the middle of a city will recieve few points. Trails, Bridges, Roads and Powerlines and Towers nearby will all affect this category.

Subjective Score – Max 20 Points
This is used primarily to balance out ratings which we feel are inaccurately or unjustly represented. Most of the time this will reflect a general alignment to our legacy rating system, but in cases where there are extreme outliers such as heavy urban development and commercialization of a waterfall (think Niagara Falls), or the raw data doesn’t reflect the grandiosity of a location property, this allows us to boost or reduce the score a bit. All waterfalls begin with 10 points, and points are added or reduced as necessary.

As stated above, the total score based on these variables is not displayed as the final score, but it is rather graded on a curve based on the highest and lowest scores possible. This is done in three tiers – one on a Global scale, one on a Country-wide scale and one on a State or Provincial scaoe. This allows us to effectively compare waterfalls around the world, within one specific country or one specific state. The grading of each scale may periodically change as we discover new waterfalls and record new data.

Not Rated

Of a final note, many waterfalls in this database will at some time display “Not Rated” within its final Rating box. This could mean one of two things. Most commonly this will simply illustrate that we don’t have enough data to properly quantify the waterfall numerically and hence we can’t effectively rate it. For the waterfalls we have recorded data for which display the same message, this means that the waterfall is not significant enough to achieve a rating. This will usually be on a Global or Country-wide scale, because (especially in larger countries) many countries possess so many waterfalls that using the very smallest waterfall as the low point on the grading curve would unfairly punish the majority of the waterfalls within that specific region. Many waterfalls which we have rated may still, however, achieve a State or Provincial Rating. Those waterfalls that we have recorded data for which recieve this “Not Rated” status aren’t necessarily bad waterfalls, they simply don’t measure up to the best waterfalls on the planet.

Be Sociable, Share!