International Scale of River Difficulty

By Tyson Stevenson

White water is classified into 6 categories depending on the difficulty:

• Class I: Smooth water but fast.
• Class II: A little bit of rough water with eddies and easy drops
• Class III: Whitewater with rapids irregular waves, back eddies. Swimming, self rescue knowledge is must.
• Class IV: Whitewater with whirlpools, high irregular waves, for experienced adventurers.
• Class V: Whitewater with dangerous obstacles, violent rapids, boiling eddies. Scouting is essential before going on such expeditions
• Class VI: Extremely dangerous unexplored rapids.

Due to interaction of river and riverbed various features are like strainers, eddies, waves, pillows and holes are formed. The passage of water through large objects, (usually boulders) causes a strainer. Holes are formed when water pours on top of submerged objects that cause the water to flow backwards which rushes over the object. Waves are fronts formed on water surface flowing down. Eddies are swirls or rotating water flow. When large volume of water suddenly comes against an obstruction, the water flows to a certain limit over the obstruction causing a pillow. The popular destinations are South Fork American river, Colorado river, Arkansas river, Salmon river, Merced, Kaweah in US. Rivers in Quebec and British Columbia in Canada. Ganga Yamuna and Teesta rivers in India. There has been concern by environmentalists due to activities of White water rafters like dredging the river bed. However white water rafting also contributes to the local economy.