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<br />17 <br /> <br />line was drawn through the poinb3 of each time period. <br />'I'he discharge relationship from the records after 1934 is <br />parallel but one third lower than the disc:ha.rge before 1934. <br />Gages 9-0470, 9-0630 and 9-0850 were analyzed to see <br /> <br />if the areas without cont]=01s showed a similar decrease. <br /> <br />Again the same time periods before and after 1934 were used <br /> <br />t;o study possible change in the calculated 50 year discharCJes. <br /> <br />See Annual Peak Flow graphs figUl:es 17 thru 19 .i.n t.he appendix. <br />The resul.ts of the compari.son were; <br />Q,... <br />~) \.., <br />BEFORE: T9""J2r-...---l~F;.;I~j~R-19 :f4' <br /> <br />GAGE NO. <br />9--0470 <br />9-0630 <br />9-0850 <br /> <br />REDUCTION <br /> <br />1,450 cfs <br /> <br />985 cfs <br /> <br />32% <br /> <br />1,120 <br />17,990 <br /> <br />BOS <br /> <br />28% <br /> <br />16,700 <br /> <br />7's <br /> <br />These gaging st:ations represent about one..."ifth of <br /> <br />the drainage area above DeBeque Canyon. The most si~rnifi- <br /> <br /> <br />cant gaqe is 9-0850 at G1enwcod Spr:c.ngs because it is t.he <br /> <br />largest drainage area of the threo gages not affected by <br /> <br />controls and diversions. U",ing to:IC drainage area as a basis <br /> <br />to proport.ion the reduction I '::.h.e[:'~! (Jaqes have an averaqe <br /> <br />reduction of 8% in the peak f.ews. <br />It i" logical t;o attribui:s L1i:o' reduction 1:0 clLnatologi-- <br />cal change. Therefore the :' :,1,\ re,Juct.:ion of the 50 YbH flood <br />as calculated from t.he Colora.do River gaging s1::ations is not <br />ent.irel1' from diversions and contc:cols" At leas'l: 8% can be <br />attributed to olimatologi.cal change, 'rhus diversions and <br />controls account for a 25% reduct.ion in t.he 50 year flood. <br /> <br />In our opinion, however, t.lle preserct:. cont:.rols and diversions <br /> <br /> <br />would have less influence on a hiqti. frequency (100 year or <br />