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HomeMy WebLinkAbout08.08.13 Summary of Precipitation DataSummary of Precipitation Data & Distribution Source: NOAA Atlas 2, Volume III Design Storm Year 24 -hour inches Source; isopluvial map 6 -hour inches Source: isopluvial map Determine 1 -hour rainfall Amount: Need 2 -yr & 100 -yr 1 -hour values 2 -year 2 -year 100 -year 100 -year 24 -hour 6 -hour 24 -hour 6 -hour 1.20 inches 0.85 inches 2.60 inches 1.80 inches Source: Figure 26 isopluvial map Source: Figure 20 isopluvial map Source: Figure 31 isopluvial map Source: Figure 25 isopluvial map 2 -year 1 -hour use Table 11, Region 2 equation = Y2 =- .011 +0. 942[ (2yr,6- hr)(2yr,6hr)1(2yr,24hr)] 2 year 1 hour = 0.56 inches 100 -year 1 -hour use Table 11, Region 2 equation = Y100 =. 494 +0. 755[( 100yr ,6- hr)(100yr,6hr) /100yr,24hr)] 100 year 1 hour = 1.43 inches Use Fig 6 to interpolate 25 -yr, 1 -hr value 1.10 inches Rainfall Distribution Time 5 10 15 30 1 2 3 6 12 24 minutes minutes minutes minutes hours hours hours hours hours hours Rainfall (inches) 0.32 0.50 0.63 0.87 1.10 0.72 0.47 0.00 0.00 Source Ratio or equation Table 12 ratio for 1 -hr 0.29 Table 12 ratio for 1 -hr 0.45 Table 12 ratio for 1 -hr 0.57 Table 12 ratio for 1 -hr 0.79 Figure 6 (includes equations noted above) Equation 5, Pg 16 = 0.341(6 -hr)+ 0.659(1 -hr) Equation 6, Pg 16 =0.569(6 -hr)+ 0.431(1 -hr) 0 Figure 17 0 M:ICREjobfiles1831 -TLT1 Worksheets) NOAA Precip Distribution.xls 25 year 818/2013 Colorado River Engineering