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<br />~JL (y <br /> <br />minimum flows is not given and no eVid/ce is provided t.lshOW that the seiection process <br />assures adherence to the fundamental requirement of ~ RCID that the flow ~ <br />"minimum" flow. Finally, it is not stated which hydrograph, Table 1 or Table 2,~eferred. <br />Since they are not iden~ only one can be the preferred hydrograph. <br /> <br />General Conclusions <br /> <br />These comments, and many of the- comments made in the review notes listed for a specific <br />section of a specific re~apPI~~h reports that address the same topic. <br /> <br />Numerous ef=Mfe statements ade in these reports are unsubstantiated, confusing or self- <br />contradicting. Furthermor: , it is surprising, given all the work performed in the area of <br />whitewater park desigF'l', that the author has not developed a quantitative measureoof ~n <br />acceptable or intended recreational experience. If' ~....->'-"'" <br />~ither report provides compelling discussion and evidence, based _ engineering analysis, of <br />, ~he hydrau.lic control for the project n~r how the st,ructures captur~~ co~trQLaJ:lg-d~vert-fl~This <br />~eec:l~ In general tgrms for the entire study reach, for both the. eXiStfr1'g and proposed \ <br />C~~.~~tiQDS, as .well ~~at e~ch structure~ Also missi~gJ[Oql, these reports, and tied to the . . <br />control Issue, IS an analYSIS of the Froude number~~-seCllJeRt depths, energy loss and stabIlity <br />of the hydraulic jumps over the range of expected flow rates for each of the proposed <br />structures. The hydraulic jumps created by the structures are a dominant feature of the design <br />and a detailed understanding of their behavior is critical. ~ l-S. \ \~~~ <br />.~ ,,~ <br />Based on the information, both provided and missing, in these documery::>lt I~. apparent that <br />the author has adopted an engineering design methodology that pre~o/T1inantly relies on past <br />experience. As discussed above, well documented experience baseo/design, both personal <br />and that of others, is a legitimate component of the design process. However, it is my oPini~ <br />that this should be complemented with, at a minimum, detailed engineering analysis and _ j <br />possibly physical modeling. ~ C~ ~ <br /> <br />The proposed profile design is not clearly defined. The report states that the U-structure is ' <br />constructed so that the upstream sill is placed at the existing riverbed level. This implies that! <br />the area immediately below the crest must be excavated to create the drop. This would ~ <br />artificially lower the downstream riverbed by the height of the drop (which was not specified). ~ <br />"[ i no evidence to show that sedimentation or erosion would not occur in this altered <br />regi~'n and that this would not have a negative effect on other sections of the river or the <br />pe ormance ,of a structure. Further~ the geometric conditions on the downstream side of <br />the structu~i11 have a significant impact on the characteristics of the hydraulic jump and <br />should be thoroughly assessed. <br /> <br />