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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br /> <br /> <br />DYNAMIC SYSTEMS <br /> <br />Streams are dynamic features of the earth's surtace that change over time, A basic understanding of the <br />physical processes that are responsible for stream form is needed in order to work within the stream <br />environment. Unlike static features on the earth's surface, such as a road, there is no template for the <br />construction of a stream, The geometry of a stream is self-adjusting in response to the flow velocity, flow <br />rate, and volume of water & sediment loading that is supplied to the system, Dver lime, changes in water <br />and sediment supply result in channel adjustments that may include erosion of the streambed or bank, or <br />channe' aggradation and the creation of sandbars, <br /> <br />" <br />, <br /> <br />As a stream increases in power and mobility it becomes less predictable, Figure VII-1 illustrates the <br />increasing uncertainty and risk that occurs with increasing power and mobility. It is important in the reha- <br />bilitation of stream channels that the physical difficulty and uncertainty associated with the work be under- <br />stood and suitable design criteria developed. Therefore, the classification method takes various combina- <br />tions of mobility and stream power and establishes class identification. <br /> <br />" <br /> <br />Figure VII-1 - The River Environment <br /> <br />~ >; <br /> <br />, <br /> <br />HighPowaf <br /> <br /> <br />, <br /> <br />Stream <br />Power <br /> <br />^J <br /> <br />Low Power <br /> <br />lIil'. <br /> <br />low Sedimenl Transport <br /> <br />HiohSedimentTransport <br /> <br />Mobility <br />Section VII - 2 <br />