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<br />43 <br /> <br /> <br />.....RADIUS OF <br />WAVELENGTH -B CURV,ATURE <br /> <br />~ --- -... <br />.-- , -... <br /> <br />/ ?zd~-~, <br /> <br />/ CK.NNEl ~ ("........" <br />~ <br /> <br />WAVE <br />AMPLITUDE <br /> <br />GEOMETRIC FEATURES OF A SnEAI~ MEANDER <br /> <br />Figure C <br /> <br />. Sinuosity, or tightness of bend, is defined as the ratio of the length <br />of the channel in a given curve to the wavelength of 'che curve. Although <br />values tend to show considerable variation, in the la:rge majority of <br />meandering streams sinuosity ranges from 1,.3/1.0 to 4/1. Streau having a <br />sinuosity of 1.5 or more are called meandering, and those below 1.5 are <br />called straight or sinuous (Leopold et al. 1964). <br /> <br />There is a significant positive correlation betw.aen channel sinuosity. <br />variability and diversity of stream depth, and stream velocity. As <br />,sinuosity increases, habitat diversity, biomass, and numbers of organisms <br /> <br />in the macroinvertebrate drift increases. Likewise, there is a direct <br />relation between habitat diversity and diversity of f1sh c01llllnlnit,ies. <br />Therefore, habitat diversity is a composite of sinuos:ities, bottc,m type, <br />depth of water, and velocity of flow. <br /> <br />The similarity of spacing of pools and riffles in alluvial stream <br />channels suggests that the development and maintenancle of pools and riffles <br />is one of the primary fluvial (1.e., produ,ced by the ,stream) processes <br />occurring in streams (Keller 1972). Furthermore, the tendency tel develop <br />pools and riffles is apparently associated with some type of wave phenomena <br />that is significant in the meandering process (Leopold et al. 1964). <br />Measurement of large numbers of pool and riffle sequel~ces strongly confirms <br />the conclusion that pools and riffles are spaced on the average of five to <br />seven times the channel width (Figure 13). <br /> <br />Meander Factor <br /> <br />The amount of meander (i.e., the amoul1t of bending) can be estimated <br />for a stream by measuring the meander distance of sel.acted segments of <br />stream channel that are visible on aerial photos or ~lpS. A "meander <br />factor" expresses the number of units of meander distlmce that are <br />sssociated with one unit of straight line clistance. ]'or example, a stream <br />that measures 5 units of distance on a strllight line basis may actually <br />extend 8 units of distance. Thus, a meando:r factor ClIO be calculated as <br />