Research Protocol for Cottonwood Ranch (2)

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intensive cross sections are placed upstream of the managed area, within the managed area, and downstream of the managed area. Streamflow will be collected at a stream gage to be placed on the middle channel of the Cottonwood Ranch property below the management activities. The gage will provide streamflow discharge for that specific channel and total river flow comparisons with the gage, Platte River at Overton, NE. Suspended-sediment concentration is collected at the streamflow gage on the middle channel. Suspended-sediment concentration and the size distribution of the suspended material provide information on changes in fine-grained sediment movement and changes from the managed section upstream. To provide a continuous record of fine-grained sediment transport, an Optical Backscatter sensor will be used. Methods 1) Topographic survey - The procedure for surveying river cross-sections employs a survey- grade global positioning system (GPS) to measure the location of bed, bank, and bar locations relative to a fixed horizontal and vertical datum. The cross-section will be oriented orthogonal to the principal flow direction in the reach considered, with the extents of the section delineated on either bank with a permanent marker. Cross section will be measured from either river left or river right depending on the surveyor's field and office data reduction preferences. The surveyor will begin at a marker on one bank and proceeds in a straight line toward the corresponding marker on the opposite bank. Rather than making equally spaced measurements of position along the section the practice is to instead define the `slope breaks' encountered. An example of a slope break could be the top of a bank and the corresponding toe of the bank. The point at which the water surface intersects an island or bank will also delineated. An important aspect of ineasuring these cross sections requires an ability of the surveyor to recognize and delineate geomorphic features such as banks, bars, high water marks, and water edge. The GPS used in the topographic survey computes the position of a rover unit relative to a known horizontal and vertical datum or base station using a satellite network and real time radio communication between the base and rover. Positions will be precise to within 2 centimeters in the vertical direction and 1 centimeter in the horizontal direction. The GPS requires a `coordinate seed' or a known initial point from which to begin making measurements. An arbitrary position could be selected but the best practice is to relate a survey to a reference marker set by the National Geodetic Service (NGS). A listing of NGS benchmarks near the Cottonwood Ranch property and the quality of the horizontal and vertical values are compiled in Table 2. In addition, a number of UGSG elevation benchmarks are located in the vicinity. To relate the research cross sections to a common reference, NPPD will set a series of bench marks near the research activity. 2) Bed /Bank Sediment Sampling- The procedures for measuring bed sediment are taken from Edwards and Glysson, 1999. The type of bed material sediment sampler selected for use is a function of the size of the bed sediment measured and the depth and velocity of the river considered. The Platte River can be safely waded during most months of a typical water year. Previous experience has shown it is practical to do wading bed material sampling in the Platte