River surfing
Claims for its origins include a 1955 ride of 2.4 km (1.5 mi) along the tidal bore of the River Severn.
A requirement for this is a flowing water with shallow depth in which the inertia of the water overcomes its gravity due to the supercritical flow speed (Froude number: 1.7 - 4.5, surpassing 4.5 results in direct standing wave[5]) and is therefore neither significantly slowed down by the obstacle nor pushed to the side.
[6] A river surfer can face up-stream and catch this wave and have the feeling of traveling fast over water while not actually moving.
Despite being many hundreds of kilometres from the nearest ocean, Munich has a reputation as a surfing hotspot,[7] offering one of Europe's best waves.
[9] Up to 100 surfers daily hit the waves in the city's Englischer Garten, the largest urban park in the world.
There, in the river Eisbach, the world's best known river surf spot,[10] the Eisbach (literally “ice brook”) wave, the flow velocity of the icy water is about 5 meters per second, at a flow rate of 20 m3/s (equivalent to a mass of 20 tons per second), and the temperature never gets above 15 degrees Celsius.
In the 2000s, transplanted ocean surfers began riding standing waves in a number of rivers in Alberta, Canada.
The most popular area to river surf around Southern Alberta is in Kananaskis district (45 min from Calgary) at a spot called Mountain Wave.
As of the early 2020s, projects of building two additional adjustable man-made river waves are well under way.
This wave is highly active during these months and the area continues to grow as a surf destination.
Salida, Colorado has a whitewater park with six different features and a thriving river surfing scene.
[36] Tidal bores occur in relatively few locations worldwide, usually in areas with a large tidal range (typically more than 6 metres (20 ft) between high and low water), and where incoming tides are funnelled into a shallow, narrowing river via a broad bay.
[41][42] Surfing the Severn bore has become a competitive sport with dozens of surfers vying to record the longest ride.
The present champion surfer is Dave Lawson from Hempsted, Gloucestershire, who has covered 5.7 miles on a surfboard.
[43] The pororoca is a tidal bore, with waves up to 4 metres high that travel as much as 13 km inland upstream the Amazon River.
Boise Whitewater Park's Wave Technician, Paul Primus, shares the dual benefit of installing recreational river features to replace dangerous low head dams everywhere.
[46] Replacing old low head dams with river recreation features can have many benefits - low head dam hazard abatement, river navigability, fish passage, flood mitigation, sediment transport, river blight removal, diversion infrastructure modernization, significant economic impact, provision of swiftwater training facilities, public health benefits, and introduce opportunities to help reduce regional youth drowning rates.
Even if the temperature is high, it is recommended to use footwear in order to avoid cuts from rocks in the river.
