Criteria for a Waterfall qualifying for the WWD
In order to effectively segregate those features which can be legitimately deemed as waterfalls from features which may be considered by some to qualify but do not meet our definitions and standards, we have created a set of criteria which a waterfall must meet for it to be included in the World Waterfall Database.
Our primary qualifier is the height of a waterfall as it is the most visually indicative of a change in elevation. Depending on the average discharge of the stream along which the waterfall occurs, we have two different qualifiers for the height of a waterfall:
- Perennial Streams – Waterfalls occuring along streams which maintain a discernable volume of water throughout the year must drop at least 15 vertical feet (4m) to qualify for inclusion in our data.
- Intermittent Streams – Waterfalls occurring along streams which run dry for part of the year must drop at least 50 vertical feet (15m) to qualify for inclusion in our data.
Additionally, the drop of the waterfall in question must conform to our definition of Waterfall:“A well defined change in slope, velocity, aeration or agitation of the water within a stream over an immediately abrupt distance, where an identifiable loss in elevation may be perceived due to non-uniformity of the underlying geologic structures.”
…and as such must have an easily identifiable top and bottom, and must fall as a result of contacting or being interrupted by solid bedrock rather than talus, boulders or rock lying on top of the earth.
Should a waterfall along an intermittent stream qualify based on height, it needs to meet a secondary requirement of flowing consistently for at least one month out of the year. This stipulation is meant to prevent rainstorm fueled waterfalls (such as those seen throughout Arizona’s Grand Canyon) from being included when they meet the 50-foot requirement.
Both of these requirements may, however, be waived if the waterfall in question has a history of recognition. Features which have names recognized by a governing body (Federal, State / Provincial, City or otherwise), or a name which has been in widespread colloquial usage for over 50 years.