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Defining a Design Storm. Define the time parameters Select storm type - 5 options Enter required parameters e.g. Depth, duration etc. Display rainfall as table and graph Accept the storm Define a 5-character descriptor. Storm Types Available. Chicago hyetograph Huff rainfall distribution
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Defining a Design Storm • Define the time parameters • Select storm type - 5 options • Enter required parameterse.g. Depth, duration etc. • Display rainfall as table and graph • Accept the storm • Define a 5-character descriptor
Storm Types Available • Chicago hyetograph • Huff rainfall distribution • Mass rainfall distribution (can beuser defined) • Canada AES (Atmospheric Environment Service) • Historic storm (user defined)
Huff storm - 1st quadrant 1st quadrant
Huff storm - 2nd quadrant 2nd quadrant
Huff storm - 3rd quadrant 3rd quadrant
Huff storm - 4th quadrant 4th quadrant
Mass Rainfall Distribution • Defined by series of uniformly spaced vertical coordinates which increase continuously from 0.0 to 1.0 • Various standard distributions for North America included with MIDUSS 98 • User defined distributions are easily defined using local data • Maximum number of points is unlimited
Historic Storm 15 valuesstill zero Last value entered by user
City of Guelph Design Storms Return a b c rperiod (mm/hr) (min) 2-years 743 6 .7989 0.4 5-years 1593 11 .8789 0.4 10-years 2221 12 .9080 0.4 25-years 3158 15 .9355 0.4 50-years 3886 16 .9495 0.4 100-years 4688 17 .9624 0.4