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<br />.. <br /> <br />t".. <br />-.J <br />IV <br />C:,JI <br /> <br />... <br /> <br />.. <br /> <br />2. Flow (mean and median monthly). <br /> <br />3. Sediment yield from watershed, mean monthly. <br /> <br />4. Temperature, water and ai r (mean and maximum/mi nimum monthly). <br /> <br />These data may be available from records of the USGS, State, USFS, SCS, <br />CE, EPA (STORET), and the WRC Sedimentat i on Commi ttee. In the case of <br /> <br />cross-sections, however, field data may need to be obtained. The primary <br /> <br /> <br />function of hydraulic simulation in present instream flow studies is to <br /> <br /> <br />predict within acceptable limits of accuracy the distribution of depths <br /> <br /> <br />and velocities within a stream cross-section at different discharges, <br /> <br /> <br />with a minimum of field time involvement (1). Types of simulation pro- <br /> <br /> <br />grams used may include Manning's equation, stage-discharge relationships, <br /> <br />or a combination of stage-discharge and Manning's equation. Manning's(4) <br /> <br /> <br />equation can make use of a single discharge measurement to calibrate an <br /> <br /> <br />empirical stage-discharge equation; at the other extreme, a stage- <br /> <br /> <br />discharge curve based on many measurements may be used for calibration. <br /> <br /> <br />The approach used should have a level of reliability in output which is <br /> <br /> <br />consistent with the overall approach to the determination of the value of <br /> <br /> <br />instream flows, i. e. for reconnai ssance or site-speci fic impact <br /> <br /> <br />appraisals. <br /> <br />G. Response Analysis <br /> <br />As a part of the methodology, curves were developed showing the changes <br /> <br /> <br />in habitat suitability at various depths and velocities for each target <br /> <br />13 <br />