How
to read a Flood Information Chart
Example: Coal Creek
|
Flooding Source & Location
|
Drainage Area (Square Miles)
|
Peak
|
Discharge
|
(CubicFt.
|
per Sec.)
|
|
10-yr.
|
50-yr.
|
100-yr.
|
500-yr.
|
|
Confluence w/ Rock Creek
|
59.3
|
5,120
|
8,740
|
10,640
|
15,920
|
|
Burlington Northern Railroad
|
36.3
|
2,300
|
3,490
|
4,120
|
6,170
|
|
U.S. Hwy. 287
|
35.6
|
2,370
|
3,480
|
4,110
|
6,160
|
|
U.S. Hwy. 36
|
27.9
|
1,740
|
3,070
|
3,820
|
6,030
|
|
McCaslin Blvd.
|
26.7
|
1,400
|
2,980
|
3,770
|
5,990
|
1) Locations given
from downstream to upstream with drainage areas getting smaller the
further upstream the location.
2) Peak Discharge refers to anticipated rate of flow during a particular
flood event given in cubic feet per
second based on an analysis of weather and other data.
3) Flood events are calculated primarily for flood insurance purposes
based on the statistical probability of a particular flood occurring
in any given year. A 10 year flood has a 10% likelihood of happening
in a given year, a 50 year flood has a 2% probability of occurring,
and a 100 year and 500 year flood have a 1% and .2% potential. Click
here for more.
4) Flash Floods occur quickly, with little or no warning. They often
happen in or near mountains where the steep slopes can serve to funnel
large quantities of water through narrow channels. Flooding in other
regions away from mountains may offer more warning time but can involve
much larger quantities of water.
|
