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<br />I, INTRODUCTION <br /> <br />The river and watershed system is an integral part of the dynamic <br /> <br />.. <br /> <br />ecosystem. Stream flows, sediment transport rates, and channel morphology <br /> <br />reflect the major responses resulting from watershed management and/or river <br /> <br />utilization activities. Knowledge of river mechanics, morphology, and water- <br /> <br />shed management is basic to assessing instream flow needs. <br /> <br />Instream flow issues often result from increased competition for off <br /> <br />stream water uses (agricultural, industrial, urban, and energy developments) <br /> <br />and public concern for environmental quality. Sources of these issues arise <br /> <br />from such development activities as: (1) the redistribution of water over <br /> <br />time and/or space to increase low flows and/or reduce flood flows, (2) the <br /> <br />construction of diversions which decrease natural stream flows, and (3) <br /> <br />changes in land use or other watershed management practices that alter the <br />water and sediment input to the stream, Such developments affect both water <br />quantity and quality and in turn change stream morphology, stage-discharge <br />I <br /> <br />relationships, substrate distribution, and fish habitat. <br /> <br />When assessing instream flow requirements for fishery habitat and <br /> <br />instream recreation, knowledge of the spatial and temporal distribution of <br /> <br />flow depths and velocities is necessary. Consequently, the Cooperative <br /> <br />Instream Flow Service Group has developed hydraulic simulation techniques for <br /> <br />the determination of the spatial distribution of various combinations of <br /> <br />depths and velocities with respect to substrate for alternative flow regimes <br /> <br />or channel configurations, <br /> <br />The purposes of the Watershed and River Mechanics Module of the Workshop <br /> <br />.... <br /> <br />were to: (1) evaluate current predictive methodologies, (2) evaluate the <br /> <br />hydraulic components of the Instream Flow Group's Incremental Methodology, <br /> <br />48 <br />