International scale of river difficultyThe international scale of river difficulty is an American system used to rate the difficulty of navigating a stretch of river, or a single (sometimes whitewater) rapid. The scale was created by the American Whitewater Association to evaluate rivers throughout the world, hence international in the title. It should not be confused with the internationally used whitewater scale, which is published and adapted by a committee of the International Canoe Federation (ICF).
Eddy (fluid dynamics)In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle.
Whitewater kayakingType of water sport Whitewater kayaking is an outdoor adventure sport where paddlers navigate a river in a specially designed kayak. Whitewater kayaking includes several styles: river running, creeking, slalom, playboating, and squirt boating. Each style offers a different way to experience the river environments.
AlluviumAlluvium (from Latin, from 'to wash against') is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is typically geologically young and is not consolidated into solid rock. Sediments deposited underwater, in seas, estuaries, lakes, or ponds, are not described as alluvium.
Whitewater canoeingWhitewater canoeing is the sport of paddling a canoe on a moving body of water, typically a whitewater river. Whitewater canoeing can range from simple, carefree, gently moving water to demanding, dangerous whitewater. River rapids are graded like ski runs according to the difficulty, danger, or severity of the rapid. Whitewater grades (or classes) range from I or 1 (the easiest) to VI or 6 (the most difficult/dangerous).
PortagePortage or portaging (CA: ; US: ) is the practice of carrying water craft or cargo over land, either around an obstacle in a river, or between two bodies of water. A path where items are regularly carried between bodies of water is also called a portage. The term comes from French, where porter means "to carry", as in "portable". Early French explorers in New France and French Louisiana encountered many rapids and cascades.
ElevationThe elevation of a geographiclocation is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotentialgravitationalsurface (see Geodetic datum § Vertical datum).
RiverA river is a natural stream of fresh water that flows on land or inside caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of its course if it runs out of water, or only flow during certain seasons. Rivers are regulated by the water cycle, the processes by which water moves around the Earth.
RapidsRapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Flow, gradient, constriction, and obstacles are four factors that are needed for a rapid to be created.Stream gradientStream gradient (or stream slope) is the grade (or slope) of a stream. It is measured by the ratio of drop in elevation and horizontal distance. It is a dimensionless quantity, usually expressed in units of meters per kilometer (m/km) or feet per mile (ft/mi); it may also be expressed in percent (%). The world average river reach slope is 2.6 m/km or 0.26%; a slope smaller than 1% and greater than 4% is considered gentle and steep, respectively.
TurbulenceIn fluid dynamics, turbulence or turbulent flow is fluid motion exhibiting chaotic changes in pressure and flow velocity. It is in contrast to laminar flow, which occurs when a fluid flows in parallel layers with no disruption between those layers.
FoamForm of matter Top of a foamy drink Foam is a two-phase material system and a type of dispersed media, consisting of gas cells dispersed in a continuous liquid or solid phase to form a cellular structure. In most foams, the gas occupies most of the volume and is divided into bubbles separated by thin films of liquid or solid material. The formation, stability and properties of foams are studied in physics, physical chemistry and materials science.*As an Amazon Associate I earn from qualifying purchases.