EARTHSC 2GG3 Lecture Notes - Flow Velocity, Dendrochronology, List Of Bus Routes In Brooklyn
5 Sep 2014
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Image: debris flow that occurred in the foothills of the san gabriel mountains north of los. When natural events are random, it is helpful to represent their frequency as an average time between past events, a recurrence interval (also known as a return time. ) Average time between floods of given size. For given-size flood, recurrence interval is: t = (n+1)/m, where, t = recurrence interval, n = total number of years in record, m = rank of flood (largest flood = 1; second-largest flood = 2; etc. , example 1: If the largest flood on river at single location was in 1997 m1997 = 1: and have 87 years of records n = 87, then recurrence interval for 1997 flood is. T1997 = (87+1)/1 = 88 years (average: example 2: If in 2007 slightly larger flood occurs, m2007 = 1 and m1997 = 2. T1997 = (97 + 1)/2 = 98/2 = 49 years (average)
