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<br />40 THE ARKANSAS RIVEF- :r:~~Q.OD OF JUNE 3-5, 1921. <br /> <br />The next serious flood in the ,Arkansas Valley, and the last one' <br />before 1921, occurred October 19-21, 1908, and affected the area east <br />of La Junta. It was due to very heavy rains. Records kept. by the <br />Amity Canal Co. at various points showed a rainfall of 6 inches <br />or more extending from Prowers to Holly. Pra.ctically all the rain <br />was believed to have faIlen in eight hours during the night or Octo- <br />ber 18. The area affected by the flood extended from La Junta on <br />the west to Lamar on the east and from the Missouri Pacific Rail- <br />road on the north to the south boundary of Oltero, Bent, and Prowers <br />counties on the south. The maximum stage of the river at Holly <br />was 11 feet on the river gage. The maximum discharge at this <br />p!jlint was estimated from cross sections and slope measurements made <br />a~ter the flood as 136,000 second-feet. The flood at the Amity dam <br />W11S estimated as greater than 100,000 second,.reet.15 <br />That this flood did not affect the upper river is shown by the <br />fact that the ma,ximum discharge or the Arkansas at Pueblo ror a <br />week prior to the, flood waS only 298 second.,feet, which showll that <br />there was no flood at Pueblo within the time it would have takim <br />for flood flow there to reach La Junta by October 19. <br /> <br />MAXIMUM DISCHARGES PER SQUARE ]~ILE PREVIOUSLY <br />RECORDED. <br /> <br />During the flood of 1921 the tributary streams had maximum dis- <br />charges per square mile that were almost unprecedented in the Rocky <br />Mountain StatE'-s. The only recorded unit discharge that equaled <br />them was that of Hogan's Gulch near Eden, Colo., a station on the <br />Denver & Rio Grande OWestern Rai.lroad bet~'i'een Colorado Springs <br />and Pueblo. Here a cloud-burst on August 7, 1904, caused a flood <br />that was estimated to have a maximum discharge of 9,640 second-feet <br />from a drainage area of 6.1 square miles, or 1,580 second...reet per <br />square mile.16 . <br />It is apparent that streams d::-a:ining small areas in the foothill <br />region subject to cloud...bursts must have had as high discharges in <br />the past, as those that caused thc recent flood, but 110 record of such <br />diseharges has been made. <br />The following table shows the greatest previously recorded unit <br />run-offs in the Rocky Mountain States, arranged in order of unit <br />magnitude: <br />, - ~'-','7 <br />"Freeman, W. n., U. S, Geol. Survey Water.Supply Paper ,271, pp, 33-40, 1010. <br />"Data furnished by Denver & Rio Grande Westl'rn nailr'oad Co, <br />