Review of Preliminary Draft Proposal

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in the peer-reviewed literature. REVIEW OF PROPOSAL The proposed management action of clearing 95 acres of woods clearly will provide wide areas with views unobstructed by trees (in addition to the existing channel) along roughly one mile of a Platte River channel (this width is calculated roughly as 95 x 43560 / 5280 = 784 feet ). The 50 measured cross sections, along the channel with clearing and the nearby control channel, will define well any erosion or deposition that occurs in those areas. The measured flow rates and depths will allow the development of relationships with those variables. The computer model will extend the range of relationships to other variables, and may provide a description of the physics of the erosion/deposition process. However, the proposed project does not measure enough cross sections downstream from the cleared areas (only 3), or enough information about the general sediment transport in the river, to calculate a measured sediment balance and determine whether downstream areas have any change in their erosion/deposition patterns caused by the clearing actions. The detailed measurements may determine that little or no erosion occurs at the cleared sites, and if so, there could be no downstream effects. Otherwise, the proposed data collection will be insufficient to determine downstream sediment effects. Fortunately, I doubt that erosion or deposition will be significant on the cleared land. Tree and brush clearing experience of the Whooping Crane Conservation Trust, Audubon, and People for Better Hunting indicates qualitatively that their cleared land does not erode noticeably. Annual or biennial maintenance clearing is needed to keep a low vegetation level on that land. This experience is logical because the flow of water over the cleared land is effectively flow on a low flood plain, with lower velocities and shear stresses than are found in the main channels. Flood plains generally are regions of deposition of the finer particles moving with flood flows. Further, I doubt that the active channel width will be appreciably increased from the current widths to the 1,150 feet referred to as desired, on page 11 of the development plan (1). Tree and brush clearing experience of the Whooping Crane Conservation Trust, Audubon, and People for Better Hunting indicates not only that the cleared land does not erode noticeably, but also that the active channel widths did not increase by bank erosion because of their clearing actions. Wide active channel widths exist in areas where the bed elevation is low enough to have sufficient flowing water on those areas to regularly erode any vegetation that tries to encroach on the channel. The proposed project is an expensive way to confirm and quantify the effects already observed at sites where woods are cleared for habitat improvement. The joint monitoring plan includes an estimated $7,500 per year to establish 5 cross sections and staff gages above and below habitat areas at both Cottonwood Ranch and Jeffrey Island, and to make annual measurements of habitat parameters. Major changes in the project would be needed to justify the combined PRESP and USGS funding at the level of this proposal ($580,000).