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Summary of notes taken during 4/12/00 phone conversation with Peter Murphy regarding data <br />needs to address sediment issues on the Platte, i.e., his response to the question: "What sediment - <br />related data do we need to collect during the first increment to evaluate the effects of the Program <br />on channel morphology and sediment balance in the Platte River ?" <br />Sediment data varies in quality <br />Primary Quality: measurements of bed morphology and sediment bed samples (for grain size) <br />• Measurements taken along permanent transects (cross- sections), repeated annually during <br />low flow <br />Permanent transect locations - minimum of one transect per bridge segment in central <br />Platte; one upstream and downstream of J -2 return; one transect each, below confluences <br />of Loup R., Elkhorn R., and at mouth of Platte. <br />Project - specific measurements should also be made along transects at and downstream of <br />habitat manipulation areas. Six to eight transects per project site. Measurements should <br />be made pre- and post - treatment, post- treatment repeated at least annually at low flows) <br />Cost estimate, approximately $3300. /transect (based on estimate of 8 transects for <br />$25,000 from Randy Parker) <br />Secondary Quality: measurements of suspended sediment concentration <br />• Most (>_90 %) of sediment in Platte moves in suspension <br />• Measurements of suspended sediment are taken concurrently with flow rate, as per USGS <br />SOP <br />• Due to level of scatter inherent in this type of data, at least 10 replications of <br />measurements are necessary, then measurements averaged. (Discussed square root <br />function in statistics, i.e., averaging 10 samples is 3x more accurate than 1 sample; <br />averaging 100 samples is l Ox more accurate than 1, etc.). <br />• Sampling should be done annually, during high spring flows <br />• Sampling locations- minimum of 2, at extreme upstream and downstream ends of central <br />Platte. Additional locations (i.e. at about Overton, and at the mouth of the Platte) would <br />also be very useful. <br />Least Quality: measurements of bed load (sediment moving immediately above stream bed) <br />• This type of sampling is unreliable (not worth doing, in Peter's opinion) due to dubious <br />accuracy of instrumentation <br />• The bed load can be calculated from other measurements <br />MCT, 5/2/00 <br />