![]() Neck cutoff channels are commonly formed the same way when an overbank flow occurs during a flood and the narrow piece of land between a bend in a meander is eroded away this is known as rush-cutting. More studies need to be done on how the magnitude of these floods and their recurrence interval are related to how often these chute cutoff channels form. ![]() Ī chute cutoff channel can form during a flood resulting in an overbank flow where water goes over the banks of the river, creating erosion of the surrounding landscape. Chute cutoff: a channel cuts directly across the land bypassing an entire meandering loop in the river and abandoning it.On the outer bends of a river, where water is flowing fastest, the river will erode away the land between adjacent outer bends and cause them to become close to each other this leads to their intersection. Neck cutoff: a river bend intersects itself.As these old meanders are cutoff from the rest of the river, a new channel, or cutoff channel, is formed. Cutoff channel Ī river constantly evolves and as it does, meanders that were once a part of the river are abandoned in favor of a route that is more efficient for a river to take. Meandering rivers trend in the direction of increasing sinuosity. Braided rivers do not follow this same convention. Between these values, a river is described as sinuous which describes those in a transitory state between the two states. A sinuosity value of less than 1.1 is a “straight” river. Meandering rivers have a sinuosity value/ratio of greater than 1.5. Three conventional categorizations of rivers or their reaches exist. It is expressed as the ratio of the distance between two distant points in a river following the middle-of-the-river course of the river as compared with the straight distance between those points. The term is equally used to describe the actual incidence of and potential tendency of a river to curve or meander over its length. Rivers are commonly described and interpreted by their sinuosity. On the inside bend of a river, the level is lower, secondary flow moves sand and gravel across the river bed creating shallows and point bars, and friction of air and perturbances of the bed act against a higher proportion of the column of water, being shorter, slowing the water to varying degrees. Meandering rivers flow higher and hence with more total flow, pressure and erosion on the outside of their bends due to forming a vortex as in a stirred coffee cup and consequently the river erodes more the outer bank. Rivers form meanders as they flow laterally downstream, see sinuosity. Cutoffs are a natural part of the evolution of a meandering river. The steeper drop in gradient (slope) causes the river flow gradually to abandon the meander which will silt up with sediment from deposition. Animation of the formation of an oxbow lakeĪ meander cutoff is a natural form of a cutting or cut in a river occurs when a pronounced meander (hook) in a river is breached by a flow that connects the two closest parts of the hook to form a new channel, a full loop.
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