Environmental Engineering Reference
In-Depth Information
A
Discharge
Rain
B
Undisturbed
Urbanized
Time (h)
FIGURE 5.8 A hypothetical hydrograph of a storm event with precipitation and runoff in
a natural area (A) and hypothetical comparison of watershed responses before and after ur-
banization (B) (after Leopold, 1994).
900
800
1931 - 1959 (before urbanization)
1960 - 1999 (after urbanization)
700
600
500
400
300
200
100
90
80
70
60
50
1
2
3
4
5
6 7 8
10
20
30
40
Recurrence interval (y)
FIGURE 5.9 Flood frequencies plotted as recurrence intervals as a function of discharge for
all recurrence intervals more than 1 year for a watershed before and after urbanization for
Seneca Creek in Maryland (peak discharge data from the U.S. Geologic Survey; computed as
in Leopold, 1994).
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