Laserfiche WebLink
<br />Heavy rains occurred over the upper portion of Fountain Creek and <br />contiguous areas and over the right bank tributaries of the Arkansas <br />River east of Rocky Ford. In southeastern Colorado, there was an <br />l8-inch storm center over southern Prowers County and a l6-inch <br />center over eastern Prowers County. <br /> <br />3-14. Major flooding occurred in the Arkansas River subbasin <br />from the headwaters of Fountain and Chico Creeks to central Kansas. <br />The flooding on Fountain Creek occurred from just below Colorado <br />Springs to the mouth. This flooding was caused principally by run- <br />off from Jimmy Camp Creek, a small tributary with a drainage area <br />of about 78 square miles. This tributary of Fountain Creek produced <br />a peak flow of about 124,000 c.f.s. which was reduced to about 47,000 <br />c.f.s. in traveling to the mouth of Fountain Creek. <br /> <br />3-15. Chico Creek, the other principal contributor to flooding <br />between Pueblo and Las Animas, produced a peak flow of 52,000 c.f.s. <br />at the mouth. This flow combined with flow in the Arkansas River to <br />give a peak of 104,000 c.f.s. at Avondale. With no appreciable in- <br />flow below the mouth of Chico Creek the Arkansas River peak flows <br />were reduced to 43,100 c.f.s. at Nepesta, to 31,700 c.f.s. at La Junta, <br />and to 22,100 c.f.s. at Las Animas. The peak from the Purgatoire <br />River at the mouth was 62,500 c.f.s. <br /> <br />IV - BASIC RUNOFF AND HYDROGRAPH ANALYSIS <br /> <br />4-01. Unit hydroqraphs.- The drainage area below the Bureau of <br />Reclamation's authorized Pueblo Dam contributing to flooding from the <br />Arkansas River at Las Animas, was divided into nine subareas. Unit <br />hydrographs were developed by synthetic methods because of insuffi- <br />cient rainfall-discharge data to substantiate natural unit hydrographs. <br />Synthetic unit hydrographs for each subarea were developed using for- <br />mulas developed in the Albuquerque District and previously used in the <br />hydrologic analyses of the Purgatoire River at Trinidad and project <br />document studies of the Arkansas River at Las Animas. These formulas <br />are as follows: <br /> <br />(CLL 0.3)0.669 <br />tp = 0.074 _ ca) <br />Sst <br /> <br />qp = 12,650 ('Sst . 0.00109) 1.08 <br /> <br />Sst is the equivalent slope of the principal stream profile. Other <br />terms are those defined in EM 1110-2-1405, Flood Hydrograph Analyses <br />and Computations, dated August 1959. Additional equations for the <br /> <br />16 <br />