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<br />E90 <br /> <br />FLOODS OF 1965 IN THE UNITED STATES <br /> <br />50,000 <br /> <br />lane Canyon <br /> <br />Speare Canyon <br />. <br /> <br />10,000. <br /> <br />" <br />z <br />" <br />'-' <br />w <br />'" <br />'" <br />w <br />a. <br /> <br />5000 <br /> <br />1;;' <br />w <br />w <br />() <br />05 <br />::> <br />() <br />" <br />w <br />'-' <br />'" <br />'" <br />:I: <br />1i <br />5 <br /> <br />1000 <br /> <br /> <br />500 <br /> <br />100 <br /> <br />501 <br /> <br />5 10 50 100 <br />DRAINAGE AREA, IN SQUARE MILES <br /> <br />500 <br /> <br />FIGlJBE 42.-Relation of peak discharges to 25~ and 50-year floods, floods of <br />July 26 near Echo, Oreg. <br /> <br />FLOODS OF AUGUST 22 IN THE YELLOWSTONE RIVER BASIN NEAR <br />GREYCLIFF, MONT. <br /> <br />By MELVIN V. JOHNSON <br /> <br />Rain from a thunderstorm of 1-hour duration on August 22 caused <br />flash floods in several SlIlJl.ll basins near Greycliff, Mont. (fig. 43), Un- <br />official reports of rainfall in the flood area ranged from 1.5 to 2,75 <br />inches. Roads, culverts, and some private property were damaged by <br />the flood runoff. <br />Indirect measurements of peak discharge were made at three sites. <br />At site 1 the peak flow was obtained by combining the computed flow <br />through a culvert with the computed flow over the road. At sites 2 and <br />3 the road was not overtopped, and peak discharges were obtained by <br />computation of flow through culverts. Table 31 shows the flood stages <br /> <br />SUMMARY OF FLOODS <br /> <br />E91 <br /> <br />109'50' <br /> <br />45' <br /> <br />109"40' <br /> <br /> <br />45'45' <br /> <br />EXPLANATION <br />.1 <br />Flood-determination point <br />Nu:mlMr ~Qrre8pqnds to <br />that i1l. table 81 <br />x2.50 <br />Preeipitation measurement site <br />Number i1ldiootes am.Q'Unt of <br />precipitation,in-inches <br /> <br />1IEV", <br />z:;:::; '" <br /> <br />c-::::\ <br />~report <br /> <br /> <br />o <br />, <br /> <br />2 MILES <br />, <br /> <br />FIGURE 43.-Location of fiood-determination points and precipitation sites, floods <br />of August 22 near Greycliff, Mont. <br /> <br />TABLE 31.-Flo~d stages and discharges in the Yellowstone River basin, August 22, <br />near Greycliff, Mont. <br /> <br />Maximum floods <br /> <br />No. Stream and place of determination <br /> <br />Drainage <br />""" <br />(sqmi) <br /> <br />August <br />1965 <br /> <br />G.,. <br />height <br />(feet) <br /> <br />Known before <br />August 1965 <br />Period Year <br /> <br />D_ <br />("") <br /> <br />1 Overfe1d Gulch near GreyelifL.m_ <br />2 Yellowstone River tributary 6 near <br />Greycliff. <br />3 Ye1lowstone River tributary near <br />Greycliff. <br /> <br />5.32____________hhh_ <br />1.03 ._h______hhU_.. <br />2.72 1960-65 <br /> <br />22_________. <br />22________.. <br />"55 <br />",1 <br /> <br />1,070 <br />577 <br />4 <br />48 <br /> <br />1963 ._.___m_ <br />22 <br /> <br />and discharges and, for site 3, gives the comparative values fOr the <br />previous highest flood of record. No previous peak discharges have <br />been determined for sites 1 and 2. Present frequency data are not aViJ,il- <br />able for such small drainage areas in this geographic area. <br /> <br />FLOODS OF SEPTEMBER 1 IN NORTH-CENTRAL KENTUCKY <br /> <br />By C. H, ~NNUM <br /> <br />Rainfall in north-central Kentucky was generally below normal be- <br />fore August 31. Rainfall on the last 14 days of August ranged from <br />1_09 inches at LaGrange and 1.31 inches at Lexington to 2.20 inches at <br />Lockport, most of which fell on August 19 and 20. Streamflows were <br />generally low during August. <br />The movement of severe thunderstorms northeastward across north- <br />central Kentucky on late August 31 and early September 1 caused <br /> <br />. <br />