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<br />E80 FLOODS OF 1965 IN THE UNITED STATES
<br />
<br />S~Y OF FLOODS
<br />
<br />E81
<br />
<br />FLOODS OF JULY 23 IN THE VICINITY OF HILLSBORO, OHIO
<br />After WILLIAM P. CROSS (1966)
<br />
<br />TABLE 27.-Flood stages and discharges, July 18-23, in northwestern Missouri-Con.
<br />
<br />No.
<br />
<br />Stream and place
<br />ofdeterin1natlon
<br />
<br />Maximum floods
<br />
<br />Flash floods from small drainage areas caused by high-intensity
<br />rainstorms can be expected to occur in Ohio in almost any year. Al-
<br />though the floods maybe annual events, they would rarely recur at any
<br />specific site. The rains that cause the intense floods are seldom meas-
<br />ured by rain gl1ges, and chan"",,' are small that .the floods will occur
<br />at any established gagiug station..
<br />Rainfall data were collected following a cloudburst storm of July 22-
<br />23 near Hillsboro, Ohio, that was notable for an unusually high-
<br />intensity rainfall .and for the large amounts accumulated, More than
<br />10 inohes of rain fell ",t some points during the storm.
<br />A bucket survey was made by interviewing hundreds of local resi-
<br />dents, and it produced adequate data to define an isohyetal map (fig.
<br />37). A number of high-intensity cells are evident, More than 6 in"hes
<br />of rain fell on an area of ",bout 140 sq mi. The intensity of the -rain at
<br />the recording rain gage south of Hill.boro is illustrated by figure 38.
<br />The maximum rate was about 3 inches in 1 hour. Both the maximum
<br />point rainfall and the average storm rainfall exceeded the 100-year
<br />frequency for Ohio (U.S. Weather Bureau, 1961).
<br />Peak discharges in streams in the storm area were relatively high
<br />(table 28). Before the storm of July 22-23, a serious drought persisted
<br />throughout the storm area, and it can be expected that the runoff pro-
<br />duced from the storm would have been greater if normal soil-moisture
<br />conditions had existed. .
<br />Indirect measurements of discharge were made at eight sites on small
<br />streams that are tributary tl> the Scioto River. Frequencies can be
<br />computed for streams having about more than 20 sq mi of drain.age
<br />area (ta:ble 28). The magnitudes of the peak discharges that can be
<br />computed are greater than 50-year floods before the peak in Rocky
<br />Fork was attenuated by storage in Rocky Fork Lake. The rate of in-
<br />crease in the contents of Rooky Fork Lake was extremely high, Calcu-
<br />lations from the maximum rate of rise .and from the cwpacity table gave
<br />an approximate peak inflow of 340 cfs per sq mi from 114 sq mi of
<br />drainage area. Storage of the floodwaters in the lake kept the outflow
<br />into Rocky Fork below flood stage. .
<br />Runoff from the storm of July 22-23 comprised most of the runoff
<br />for the month. The 'aoverage storm rainfall above Rocky Fork Lake
<br />was about 6 inches and that abo"" the Barrette Mills gage waS about 5.5
<br />in"hes. Runoff for July at the gage adjusted for storage changes in
<br />Rocky Fork Lake, was 2.66 inches. Runoff for July not associated with
<br />the storm of July 22-23 was of the order of only 0,1 inch, Thus, the
<br />ratio of runoff to storm rainfall was about 50 percent.
<br />
<br />Drainage
<br />"",.
<br />(sq,mi)
<br />
<br />Known befor.e
<br />July 1965
<br />
<br />July
<br />""
<br />
<br />G..,
<br />height
<br />(feet)
<br />
<br />Discharge
<br />-"'-
<br />Cfs teMe
<br />interval
<br />(y",,)
<br />
<br />Period Year
<br />
<br />Wakenda Creek basin
<br />
<br />37 Wakenda Creek at Carroll-
<br />ton.
<br />
<br />248 1948-65____ 1948, n_nn........_.. 7,000__nnnn
<br />1960
<br />mn....n.n~~~~nn...ii. T~:~ m-s;wy.-'----T-
<br />
<br />Grand River basin
<br />
<br />38 O'Neill Branch at Osborn. _.
<br />39 Shoa1-CreeknearTurneY_.n
<br />40 Shoal Creek: near Braymer...
<br />
<br />0.801955-65..._ 19M 24..20
<br />___n.m_mm_.__ 19 18.28
<br />3~.3 'i957:G5::::..i9M" .....~~. nn29:05-
<br />..._nn_.n_U..___ 22 26..00
<br />
<br />1,32Onmnn_
<br />510 6
<br />9,640 11.2
<br />126,000 ..........
<br />~600 2
<br />
<br />Lamine River basin
<br />
<br />41 Sonth Fork Blackwater
<br />River near Elm.
<br />42 Blackwa.ter River at Valley
<br />City, .
<br />43 Bla.ekwater River at Blue
<br />Lick:.
<br />
<br />16.4.. 1951.._m_ 1951 14.8 (5) mnm._
<br />.~:~::::..~~.:m'ifl ll~2 ~::g ------is..
<br />547 1958--65__00 1960 ___h_..._______n 66,500 n___nn_
<br />1961 m"n' 31.75___mmm___m__
<br />..._nn_n_nnnn 20 31.38 ~57,ooo 11.4
<br />1,120 1922--33, 1928 w_.__. 41.25 54,000 ____n..._
<br />1938-65.
<br />...n___nn_....... 23 37.50 26,000 5
<br />
<br />Missouri River maln stem
<br />
<br />44 Missouri River at Boonvillen 50.5,700
<br />
<br />1844.___m 1844
<br />_~~=:::n::~~._-nn23-
<br />
<br />32.7 710,000 _...._..._
<br />32.82 .500,000 ........n
<br />26.05 253,000 munm
<br />
<br />Osage IUver basin
<br />
<br />45 West Branch Crawford
<br />Creek near Lees Summit.
<br />
<br />839nn..nn
<br />000 20
<br />
<br />0.80 1955-65____ 1960
<br />
<br />15.57
<br />19 15.73
<br />
<br />Missouri River main stem
<br />
<br />10 46 Missouri River at Hermann.._ 528,200
<br />
<br />184L_____ 1844 35.5 892,ooom__mn
<br />1897-1965__ 1903 .n.n_nnn_n_. .676,000 n_u_~n_
<br />1951 ""-24- 33.33__mmm____nn_
<br />n_n._u..n___nn 25.40 256,000 ..u....__
<br />
<br />I Ra.tio of peak discharge to 5O-year tiood.
<br />J .A.1fected by backwater from ice.
<br />: ~~~~~ ~ ~u~t~ from gage; fIOQds of 1951 and 1965 reached'stages of 20.0 and 19.7 ft respec-
<br />tivelyat the same site.
<br />5 Unknown.
<br />o Peak stage occurred 2 days before peak: discharge.
<br />7 .A.1fected by backwater and overfiow from Missourt River.
<br />S Levee break; peak: diseharge oeeurred after crest and at stage of 28.0 ft~
<br />; Oceurred 5 hOurs before peak: stage.
<br />10 This station is not shown in figure 33.
<br />
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