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<br />the Wcst Fork ccntering. The 1% raintlood peak now from the frequency curve for Rico is 2,440 <br /> <br />cfs. Based on the observed rainflood record, the West Fork centering, not the East Fork <br /> <br />centering, produces reasonable results at Rico. The 1% raintlood hydrograph at Dolorcs from the <br /> <br />West Fork centering also compares favorably with the Dolores flow frcquency curves. Therefore, <br /> <br />the West Fork centering was used with the HMS modcllo generate the 1% raintlood hydrographs <br /> <br />for the Upper Dolores Rivcr watershed. <br /> <br />Table 17 presents a comparison bet\"'cen the IIMS model (West Fork centcring) 1% <br /> <br />hydrographs at thc Rico and Dolores gages and the now frcqucncy curves for the gages. For the <br /> <br />3-day duration, the hydrograph ....olumes are noticeably smallcr than the flow frequency curve <br /> <br />volumcs. The I % flow hydrographs are the result of a 2-day general rainstonn. MosI of the <br /> <br />higher magnitude volumes (3 days and longer) used for the raintlood now frequency curves are <br /> <br />tor late June rain-on-Iate-snowmclt events, when melting snow contributes additional volume to <br /> <br />the falling limb oflhc hydrograph. <br /> <br /> Table 17 <br />Frequenq Cun'es Compared to IBIS -'Iodel Results <br />I % Chance Exceedence Storm (\Vest Fork Centering) <br /> Dolores Rivcrbc10w Rico (cfs) <br /> Peak I-day 3-day <br />F~ucncy , 11,\IS fl't'qucncy I m.ts Frequency Il~IS <br />Curve I ~"dd CW'-'e \lodel ('UJ\.e I Model <br /> I I I I <br />2,440 2.290 1,590 \.210+ 1,150 620 <br /> I I , <br /> Dolores River at Dolores (cfs) <br /> Peak I-day 3-da <br />Frequency I H\IS F~u<:IlCY I lI~lS frequency I IIMS <br />Curve \lodel Cur,..e ~Iodd C'up..e MO<kl <br /> I I I I <br />] ].700 11.700 6.260 ! 7,000+ 5,070 3,680 <br />+I-day represents maximum 2-1-hour volume <br /> <br />34 <br />