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<br />. <br /> <br />7 <br /> <br />. <br /> <br />2.2.1.1 Straight Channels <br />A straight channel can be defined as one that does not follow a sinuous <br /> <br />course. Truly straight channels are rare in nature. Although a stream may <br /> <br />have relatively straight banks, the thalweg, or path or greatest depth and <br /> <br />velocity along the channel, is usually sinuous. Leopold, Wolman, and Miller <br /> <br />(l964) assumed a sinuosity of l.5 as the division between meandering and <br /> <br />straight channels. It is suggested that a better value is about 1.3. The <br /> <br />sinuosity of a river is defined as the ratio of thalweg length to valley <br /> <br />distance. Sinuosity varies from a value of unity to a value of three or more. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />2.2.1.2 The Braided Stream <br /> <br /> <br />A braided river is generally wide with poorly defined unstable banks. <br /> <br /> <br />It is characterized by a relatively steep, shallow water course with multiple <br /> <br /> <br />channels divided by bars and islands. Braided rivers are generally caused <br /> <br />by (1) overloading, that is, the stream may be supplied with more sediment <br />than it can carry resulting in deposition of part of the load, and (2) steep <br />slopes which produce a wide shallow channel where bars and islands form <br /> <br />rcalli ly. Channel bra:iding is one of many river patterns that can be in quasi- <br /> <br />equilibrium depending upon discharge, sediment load, and transporting ability. <br />The braided stream is difficult to control. It is unstable, changes. its <br />alignment rapidly, carries relatively large quantities of sediment, is wide <br /> <br />and shallow even at flood stages, and it alters its braiding pattern in a <br /> <br />somewhat unpredictable manner. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />2.2.1.3 The Meandering Channel <br /> <br />A meandering channel is one that consists of alternating bends giving <br /> <br />a continuous S-shape appearance to the plan view of the river. The meandering <br /> <br />river consists of a series of deep pools in the bends and shallow crossings in <br /> <br />. <br />