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<br />RANDIKE.DAT <br /> <br />The second file created was RANDIKE. DAT" which modeled <br />the effect of the 1986 levee extension on flood water surface <br />elevations. The location of the ext:ended levee was plotted <br />on the topographic work map and surveyed levE~e top elevations <br />were indicated along the levee. The closest cross sections <br />to the levee extension were section 42.0 and 43.0. The <br />surveyed levee top elevations were projected onto the closest <br />point on the nearest of the two cross sections and the cross <br />section elevation was changed to the levee top elevation at <br />those locations. The projection of points from the levee <br />profile to sections 42.0 and 43.0 is; shown on the attached <br />copies of the work map. The elevation of other points on the <br />cross section were interpolated between thesE~ projected <br />elevation points. Where the levee -t.urned away from the two <br />sections, the levee elevations were no longer projected onto <br />the cross sections, but the ground .elevationfl along the cross <br />sections were adjusted to maintain t.he last levee top <br />elevation until the natural ground elevation rose above the <br />levee top elevation. Table 3 in thle main text shows the <br />change in elevation of the 100-year flood dUE! to -the existing <br />levee. <br /> <br />The levee extension crossed in.to the Frs left bank <br />floodway near cross section 42. Th,e floodway in the <br />RANDIKE. DAT file was modified to not_ included the levee <br />extension. The original file model,ed the floodway using <br />encroachment method 4. To modify th.e floodway, section 42 <br />was changed to encroachment method 1 and the left bank <br />encroachment was set to a station th.at would take the <br />floodway around the end of the leve'~_. This change did not <br />cause the 1 foot rise criteria to b,~_ exceeded. <br /> <br />NEWDIKE.DAT <br /> <br />The final file used in the Rangely study was <br />NEWDIKE.DAT. This file was modeled a potential extension of <br />the levee on a new alignment. sinc,~ the chosen levee <br />alignment was almost perpendicular 1:0 the cross sections, the <br />effect of the levee was included in the model using ET <br />encroachments. A method 1 encroachment was made on the left <br />bank of each cross section at the lc)cation of the potential <br />levee, simulating a high enough -to block flo.r from all flood <br />events. The 1988 levee extension modeled by the RANDIKE.DAT <br />file was considered removed and -the cross section geometry <br />was as in the RANGELY.DAT file. <br />