The Characteristics and Formation of Meanders

Meanders are sinuous bends in a rivers middle and lower courses. In low flow conditions, alternating pools and riffles are formed along the river bed. The river channel is deeper in pools so it has great energy and more erosive power. Energy is lost as the river flows over a riffle be provoke of friction. These cause the rivers flow to become uneven and maximum flow to be concentrated on one gradient of the river, causing lateral erosion on one side, creating an outer(a) concave bank.Deposition takes place on the former(a) side of the bend, creating a convex bank. The cross-section of a meander is asymmetrical. The outer bank forms a river drop or a bluff with a deep pool close to the bank, mainly because of the fast flow, hydraulic action and abrasion. The inner bank is a gently sloping deposit of sand and gravel, called a mention bar. Meanders are maintained by a surface flow of water across to the concave outer bank with a balancing subsurface return flow back to the convex in ner bank.This corkscrew-like achievement of water is called helicoidal flow. In this way, eroded material from the outer bank is transported away and deposited on the inner bank. The combining of erosion and deposition exaggerates the bends until large meanders are formed. Sometimes, oxbow lakes are formed when the neck of the loop of a meander is broken through, and the new cut eventually becomes the main channel, leaving the formed channel close off by deposition.