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<br />2) A simulation similar to the "existing condition" simulation with the <br />diversion of water (hence sediment also) at the Ft. Lyon Canal set to zero. <br />This reflects the situation anticipated if the Ft. Lyon Canal were to cease <br />operation entirely. The results of this simulation are shown on Figures 4.23 <br />and 4.24. This simulation is shown on Table 4.4 as "NOFL". <br /> <br />4.6 Interpretation of simulation Results <br /> <br />Results of long-term numerical simulations of stream bed profile evolution <br />should always be interpreted comparatively rather than absolutely. Thus, the <br />predicted changes in bed elevation, for example. at various locations within <br />the study reach under project conditions, should be compared with those <br />predicted under "existing" conditions to obtain an understanding of relative <br />project performance. <br /> <br />Conclusions reached from analyzing the simulation results are highlighted <br />below: <br /> <br />. Although aU four projects exhibit net aggradation over the study <br />period, it is significantly less than would be expected without the <br />project (about two-thirds). <br /> <br />. <br /> <br />Levee alignments two and three produce slightly <br />deposition than do alignments one and three. This <br />the deposition occurring over a lesser width. <br /> <br />more depth of <br />is probably due to <br /> <br />. The levees plus the l75-foot low-flow channel produce slightly more <br />depth of deposition than without the low-flow channel. Again this is <br />probably due to the deposition being placed over a smaller area. <br /> <br />. The implication of the above two points is that the differences <br />between the two north bank levee alignments is not significant for <br />the long-term analysis. It may be for the single event analysis, <br />however. <br /> <br />. A slight reduction in aggradation (about 5~) would occur if the Ft. <br />Lyon Canal retained all the sediment it diverted. <br /> <br />. An increase in aggradation (10-15~) would occur if the Ft. Lyon Canal <br />ceased operation entirely. <br /> <br />. A decrease in deposition within t1., project subreach is likely to <br />result in an increase in deposition downstream of the project. <br />Compare for example, in Table 4.5, the change in bed elevations at <br />section U93.0-U94.2for projects 1 and 2 to existing conditions. <br /> <br />42 <br />