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<br />As the District project planning effort proceeded, it became apparent that <br />detailed project geometries could not be developed for the range of project <br />configurations that needed to be analyzed. It was agreed, therefore, at the <br />12 September 1984 progress review meeting, that the District would provide HEC <br />with approximate levee and channel alignments. The HEC would then select <br />appropriate cross sections for the HEC-6 simulations. The levee and channel <br />alignments were provided on a I" = 200' topographic map with a 2' contour <br />interval. The HEC selected cross sections to describe key features of the <br />levee and channel alignments; these sections were digitized by hand into HEC-6 <br />input format. Two levee alignments (1 and 2) were identified on the north <br />bank and one on the south bank (3) (see Figure 5.1). these were to ~e analyzed <br />with and without a 175 ft. wide low-flow channel. Thus, a total of four <br />project configurations were simulated. These configurations are identified in <br />Table 4.2. Thalweg profile plots through the project subreach with and <br />without the low-flow channel are shown in Figure 4.1 <br /> <br />Table 4.2 Project Configuration Numbers <br /> <br />Levee Alignments <br />1 & 3 <br /> <br />Levee Alignments <br />2 & 3 <br /> <br />with 175 ft. <br />Low-Flow Channel <br /> <br />#1 <br /> <br />#2 <br /> <br />Without 175 ft. <br />Low-Flow Channel <br /> <br />#3 <br /> <br />#4 <br /> <br />To locate the project sections within the 100-mile study reach, the <br />highway bridge at La Junta was used as a common reference point. The end <br />points of the project sub reach were therefore determined to be at river miles <br />ll96.4 and 1200.5. Note: the project-subreach length for the project with a <br />low-flow channel is less than the existing-channel-subreach length due to <br />planned straightening of the river centerline. Five cross sections were <br />selected within the project subreach; these are identified in Table 4.3. <br />Plots of the cross sections used for the four project configurations analyzed <br />are provided in Appendix D. <br /> <br />13 <br />