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<br />Crib .. A frame structure, filled with earth or stone ballast, designed to absorb energy and <br />to deflect streamflow away from a bank. <br /> <br />Critical sh<= stress - The minimum amount of shear stress exerted by passing stream <br />currents required to initiate soil particle motion. <br /> <br />Cross section - A diagrnm or drawing cut across a channel that illustrates the banks, bed, <br />and, sometimes, water surface. <br /> <br />Crossing.. The relatively short and shallow reach of a stream between bends; also called <br />a crossover. <br /> <br />Current.. Water flowing through a channel. <br /> <br />Cut bank .. The concave wall of a meandering stream. <br /> <br />Cutoff - A new, relatively short channel (natural or artificial) fonned when a stream cuts <br />or is realigned through the neck of an oxbow or horseshoe bend, A cutoff can <br />also develop as successive high-water flows develop a chute across the <br />inside of a point bar. <br /> <br />Deadman .. A log or block of concrete buried in a streambank that is used to tie in a <br />revebnent with cable or chain. <br /> <br />Degradation (bed) - A progressive lowering of the channel bed due to scour. <br />Degradation is an indicator that a change in the stream's discharge and/or <br />sediment load characteristics is laking place. <br /> <br />Dike (hardpan!, groin, spur, jelly) .. A structure extending from a bank into a channel <br />that is designed to (a) reduce the stream velocity as the current passes <br />through the dike, thus encouraging sediment deposition along the bank <br />(penneable dike) or (b) deflect erosive currents away from the streambank <br />(impenneable dike). <br /> <br />Discharge .. Volume of water passing a given point during a specified time, usually <br />measured in cubic feet per second. <br /> <br />Distressed streambank.. A bank that has (or is) suffering erosion or failure. <br /> <br />Drainage basin - An area confined by drainage divides, often having only one outlet for <br />discharge. <br /> <br />Dredge material - Soil that is excavated from a stream channel. <br /> <br />Drop struclure - A grade control structure that provides for a vertical drop in the channel <br />invert between the upstream and downstream sides. <br /> <br />Eddy current.. A vortex-Iype motion of a fluid flowing contrary to the main current, <br />such as the circular water movement that occurs when the main flow <br />becomes separated from the bank, <br /> <br />XVI <br /> <br />Colorado Erosion Control Manual <br />