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<br />", <br /> <br />(' l ., <br />ooo!: .~, <br /> <br />.. <br /> <br />.. <br /> <br />2. Platte River Hvdraulic and Sediment Characteristics <br /> <br />The objective of the proposed task for sediment transport is to describe <br />how the Platte River channel will respond under various flow scenarios <br />and sediment yields. The work will explain the relationship between <br />sediment transport and the channel geometry in the Platte River between <br />North platte and Chapman, Nebraska. Changes in flows and sediment <br />transport into the Platte River could result from operational changes of <br />the North Platte projects or Colorado-Big Thompson projects. <br /> <br />Previously, researchers have reported on the historical trends in the <br />channel morphology of the Platte. These reports were reviewed in the <br />Reclamation study entitled "Platte River Channel Characteristics in the <br />Big Bend Reach," April 1988. The results of this study indicate that <br />the Platte experienced a decrease in sediment supply as mainstem <br />reservoirs were constructed. This reduction in historical sediment <br />loads was found to be a major cause of channel narrowing. Presently, <br />the Platte appears to be in a state of quasi-equilibrium in terms of <br />sediment transport between Overton and Grand Island, Nebraska, as <br />sediment inflow to this reach is essentially equal to sediment outflow. <br /> <br />This quasi-equilibrium should continue unless the sediment supply to the <br />Platte River is changed or the flows between 1,000 cfs and 10,000 cfs <br />are significantly changed to alter the effective transport of sediment <br />through the Platte River. <br /> <br />The work effort to develop a sediment transport analysis for use in <br />project evaluation was begun during the prairie Bend Unit study in <br />fiscal year 1989. Collection of sediment data continued in 1990 under <br />this evaluation and is expected to continue in later fiscal years as <br />funding becomes available. A Plan of Study titled "Platte River <br />Hydraulic and Sediment Characteristics" was in 1989 as part of the <br />Prairie Bend Unit investigation. The 1989 plan is being followed in <br />this evaluation. <br /> <br />The details of this work effort can be <br />original schedule for doing this work. <br />collection work has been accomplished, <br />funding becomes available. <br /> <br />found there along with the <br />To date, much of the field data <br />and the study will continue when <br /> <br />3. SDecies Habitat Needs <br /> <br />Threatened and endangered species needs are being defined by the habitat <br />that the species are currently using on the North Platte, South Platte, <br />and Platte Rivers. These habitats are quantified and qualified by the <br />physical characteristics that describe the habitat. The physical <br />habitat characteristics have been described in various workshops and <br />publications. <br /> <br />17 <br />