Engineering and Contracting . eet walUs Brick Cement Street pavements Asphalt, brick, wood Granite block Macadam and cobble Gravel and poor Unpaved yards and Tributary to paved gutters Not tributary to paved Area insq. ft. Per cent of total area. ,,900 ,400 i27,666430,000 630,266 133,100 612,300 46,500 ?. 55 Total Impervious coefficient for district, degree of imperv- iousness. .» . Equivalent imper. area sq. ft. 1,499,
Engineering and Contracting . eet walUs Brick Cement Street pavements Asphalt, brick, wood Granite block Macadam and cobble Gravel and poor Unpaved yards and Tributary to paved gutters Not tributary to paved Area insq. ft. Per cent of total area. ,,900 ,400 i27,666430,000 630,266 133,100 612,300 46,500 ?. 55 Total Impervious coefficient for district, degree of imperv- iousness. .» . Equivalent imper. area sq. ft. 1,499, .40 . . ,950 535,676 99,825 244,920 9,300 1,037, ,405 Per cent totalarea This curve is higher than the curves whichhave been adopted in several other places,but appears to be fully warranted by the rain-fall data accumulated in Cincinnati since 1871and particularly in view of the rainfall datasecured by means of the automatic recording. Fig. 3. Plat of Storm Water Run-off Curves for Cincinnati. in which i=intensity of precipitation and T=duration of period under consideration. Ithas not, however, been deemed wise to in-clude the extreme storm of May 20, 1902,which, based on present records is not likelyto occur oftener than once in 15 years andprobably will recur at even greater intervals. rain gage of the U. S. Weather Bureau duringthe last 15 years. The topography of Cincinnati is such thatthe time of concentration in most of thesewers is very short, this making that partof the curve dealing with intensities forperiods of from 5 to 30 minutes rather more important than that part dealing with intensi-ties of periods greater than 30 minutes. The intensities indicated by the curve havenot been exceeded materially except bv onestorm, that of May 20, 1902. The storm ofJuly 17, 1912, slightly exceeded the intensityindicated by the curve but the excess lies wellwithin the limits of unavoidable
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherchicago, bookyear19
