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Conveyance Loss versus Main Canal Length <br />Most of the ditch company representatives provided loss percentages for the irrigation <br />season. As shown in Table B-1, reported conveyance losses for the large ditch systems <br />range from 10 to 50 percent, with an average of 23 percent. Figure B-1 shows the <br />estimated ditch losses as a fraction of the total river head gate diversion versus the length <br />of the main canal. An attempted relationship between ditch loss and main canal length <br />resulted in a low coefficient of determination (r2), which indicates minimal correlation <br />between the data. However, the data indicates that, in general, as canal length increases, <br />ditch losses increase. <br />0.60 - <br />~. <br />>_ 0.50 - <br />0 <br />H <br />o ~ 0.40 - <br />~ o <br />o <br />~. <br />U ~ <br />~. <br />~, ~ 0.30 - <br />~ ~ <br />~ ~ <br />O ~ <br />~ x 0.20 - <br />U <br />T <br />N <br />7 <br />0 0.10 - <br />C..) <br />0.00 - <br />Figure B-1 <br />Conveyance Loss versus Canal Length <br />y = 0.1225x°.146 <br />~ ~ ~ <br />R~ = 0.064 <br />• ~• ~ <br />0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 <br />Canal Length (miles) <br />In some instances, it was unclear whether the ditch system losses provided by the ditch <br />companies were for the main canal only, or included parts of the lateral delivery system. <br />In addition, some of the main canals become laterals and, therefore, there was uncertainty <br />involved with measuring the main canal lengths. <br />Conveyance Loss versus Canal Capacity <br />Canal capacity often provides a good basis for estimating conveyance loss, since it can be <br />representative of overall system size as well as the wetted perimeter. Figure B-2 <br />illustrates conveyance loss versus the flow capacity of the ditch. The data illustrated in <br />Figure B-2 indicate, that, in general, irrigation ditches with greater flow capacities may <br />have greater ditch losses. However, the coefficient of determination (r2) indicates that <br />there is minimal correlation between the two variables. In addition, many of the flow <br />capacities for the canals used in the analysis were obtained from HydroBase, which <br />reports capacities based on total decreed water rights or historic maximum daily <br />discharges, either of which may not accurately represent the current ditch configuration. <br />Page B4 of B9 <br />