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<br />nl",~(".,O <br />U cJ .1.. V oJ ;;J,ffected Environment & Consequences <br /> <br />3- t7 <br /> <br />Impacts of Development Alternatives <br /> <br />The kinetic energy brought into the system by the additional hydropower flows between <br />Montrose and Delta is sufficient to cause some channel adjustment, as noted in Table 3- <br />11. If the river could not widen, there is a potential for slight bed lowering in about 10 <br />percent of the affected river length of 27 miles. However, the banks of the Uncompahgre <br />River are much more easily eroded than the channel bed. Therefore, channel adjustment <br />would be expected to occur as channel widening rather than degrading. This is a typical <br />response in gravel-bed rivers such as the Uncompahgre. In order to determine a <br />conservative estimate of the amount of widening, it was assumed that the bed was fixed <br />and that all channel adjustments would occur through bank erosion. <br /> <br />Parker found that the hydraulic geometry of gravel-bed rivers with a normal upstream <br />sediment supply tended to adjust itself until the Shields value reached about 0.04. <br />However, if the upstream sediment supply were interrupted, adjustment to true incipient <br />conditions ('tc = 0.03) may be more accurate. The proposed Project would re-route some <br />irrigation flows that once were delivered via the South Canal. This change is likely to <br />reduce, though not curtail upstream sediment supply. Thus, the actual Shields value <br />should lie between 0,03 and 0.04. Calculations were made using both values to provide a <br />range of potential widening. Results are shown in Table 3-12, 3-13, and 3-14. <br /> <br />AS Lateral Hydropower Project <br /> <br />July 2000 <br /> <br />R <br />J <br /> <br />- ~., " - ' <br /> <br />