Inevitably, once sinuous flow is established it causes the river to collide with the banks and results in erosion. They interfere with upper layers of water and cause them to move in a more exaggerated pattern of sinuosity. It is thought that the frictional drag exerted on the water by the riverbed and banks causes lower layers of water to move more slowly and in a sinuous manner. These, combined with the natural sinuosity (the movement of a river in an S shape across the landscape) of water leads to different rates of erosion and deposition. helicoidal flow – corkscrew movement of water which is thought to transport eroded material downstream from one meander bend to the next.turbulent flow – horizontal and vertical eddies in the water sometimes producing mini-whirlpools.laminar flow – horizontal movement in a plane.The initial cause of meandering rivers is related to the way in which different types of flow within a river: They can vary in size, but generally have deposits of different sized sediment on the inside of the bend called a slip-off slope or point bar, and a concave section on the opposite bank of the river on the outer bend called a river cliff or bluff. Meanders are the characteristic bends in a river that are found all along the length of a river but particularly in the middle course. The most obvious example of this is a meander. Many landforms are formed in the middle course as a directĬonsequence of the relative energy balance changing, resulting in both erosionĪnd deposition. River energy fluctuations along its course leads to a dynamic environment whereby the form of the river can change season by season. The river also starts to deposit load due to variations in energy in the channel cross-section and longitudinally (caused by differences in geology, gradient, land use and weather conditions). This enables the river to erode laterally as well as vertically, thus widening the river channel. Of water, as well as the fact that the high level of gravitational potentialĮnergy which was found in the upper course of the river has been converted to More tributaries have joined the main channel, leading to an increased volume In the middle course of a river the gradient decreases (itįlattens out) and the discharge increases.
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