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MAIN FLOOD SEA~ON for the Arkansas River slJbtlasin above John Martin Dam is during the late spring and summer months. Late spring sno~ etorms in the highe~ elevations and high intensity rains over the plains region in conjunction ~ith the physicsl features of the watershed can produce the rapid concentration of runoff that characterize~ flash floods of high oask flows, small volu~os. and short durations. about 10 feet in 6 hours at a maximum rate of 4.2 feet per houri and Goodnight Arroyo wouid rise about 4.9 feet in 6.S hours at a ~aximum rate of 1.1 feet per hour. . . . VELOCITIES or WATER during the Standard Project flood would range up to about 24 feet per aecond (approximately 16 miles per hour) in the main channels of the three streams. Velooities outside of the main Channels would vary widely, depending upon location, but would reach about 6 feet par seco~d (~pproximately 4 miles per ~our) in eome areas. Theae high velocities during e ~~jor flood w~uld be extr~ffialy J~garou~ to lif~ ~~ properly. Velocities grester than 3 fest per second combined with depths of 3 feat Or more are generally considered hazardous. " " , I fLODDDAJI1AGE PREVENTION MEASUR[S prasentlycons1"t of levees con_ structed in ths lower reachea of Wild Horse_Dry Creak and Dry Creek near their ~outhe on ths Arkansas River. Regulatory city and county zoning ordinance" exist whiCh govern development in "paci_ fied special flood plain districts along fountain Creek, Dry Creak, Wild Horse_Dry Creek, and the Ark~nsa8 River. Channelization on 1lI1ldHorse_Dry Creek is propoeed in the Corps of Engineors "Report on Review Survey for flood Control and Allied Purpoees _ Arkansas River and Tributarie.. above John Martin Dam, Coloredo. ~ . . . . . . . . . fUTURE fLOODS of greater magnitude can be expeoted, but the Standard Project Flood repf8sents the raaeonable uppsr limit of expected flooding. floods the size of the Intermediete Regional Flood have occurred in the past and will OCcur in the future. Comparisons beteeen future and past floods cannot be mdde due to the laok of hi"toric flood data on the subject streama. However, future flood demagaa would be more extensive due to the continuin~ development and greater U8a of lend in the respective flood pleina. DURATION Of FLOODS on the subject tributaries ~ould be reiatively short ae cc>opared to those 0" the Ihkan&",~ River. for tha lnter- "ediata Regional flood and Standard Project flOOd, duretion above bankful 8t~ge would "vara98 about 20 huurs and 22 hours, respec- tively, on Wild Horse_Dry Creek, ..nd about 10 houre and 11 houre, reepectively, on Goodnight Arroyo. Thera ~ould be no durati~n "bove lmnkful ata~" fo. Dry Cl'~"k ". tll.,,,~ nue~ "r~ ~onlullLaJ within its banks. During the Intermediate Regional flood, Wild lIor!le-DryCreekwouldrifleabcut16feetinlOhcursata ma~imu~ rete of 3.1 feet per hour; Dry Creek ~ould ris9 about 9 f..at in 6 houu at a ,.,,~l",u," tate of 4.2 feet pOll' hour; and Goodnight Arroyo would ri!l9 about 4.3 feat in 6.S hours at a ma~imum rate of 0.8 feet per hour. During the Standard Project Flood, Wild Horse_Dry Creek would riao about 21 feet in 10 houre et e meximull\ rate of 4.6 r"at per hour; Dry Cre..k ~ould ri~.. . . . , ,