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<br />Example 7,1- Determine the storm arrangement using the alternating blocl{ using the
<br />following information obtained from NOAA Atlas 2 - Precipitation-Frequency Atlas of the
<br />Western United States - Volume III - Colorado,
<br />
<br />10-minute rainfall amount=
<br />30-minute rainfall amount=
<br />1-hour rainfall amount=,
<br />2-hour rainfall amount=
<br />3-hour rainfall amount=
<br />6-hour rainfall amount=
<br />
<br />1.21 inches
<br />2,11 inches
<br />2,68 inches
<br />3,06 inches
<br />3,35 inches
<br />3,80 inches
<br />
<br />Solution:
<br />
<br />1. The rainfall amounts from above were plotted and values between known points were
<br />interpolated and put into the second column of Table 7.1.
<br />
<br />2, Table 7,x shows the final storm arrangement.
<br />
<br />Table 7,1
<br />
<br /> Arranged
<br /> Accum Incr. Incr, Rainfall
<br />Time Rainfall Rainfall Rain Infensijy
<br />(min,) (inches) (inches) (inches) (in/hr)
<br />10 1.21 1.~~1 ,02 ,12
<br />20 1.66 Afi ,02 ,12
<br />30 2,11 .4fi .02 ,12
<br />40 2,31 .20 ,02 ,12
<br />50 2,50 .1€f ,03 ,18
<br />60 2,68 .18 ,03 .18
<br />70 2,76 ,08 .03 .18
<br />80 2,84 ,08 .03 ,18
<br />90 2,90 ,06 ,04 .24
<br />100 2,96 .06 .05 ,30
<br />110 3,01 .05 .05 ,30
<br />120 3.06 .05 ,05 ,30
<br />130 3,11 ,05 .06 ,36
<br />140 3,16 ,05 ,08 .48
<br />150 3,21 .05 .18 1.08
<br />
<br />Colorado Flood
<br />Hydrology Manual
<br />
<br />DRAFT
<br />
<br />7,7
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