Historic Flooding of May 7, 2009 for the City of Montgomery, Alabama.

Historic Flooding of May 7, 2009 for the City of Montgomery, Alabama

Torrential rain caused severe flash flooding in Montgomery and surrounding areas on May 7, 2009. The River Region experienced a line of severe thunderstorms having widespread rainfall totals of six to eight inches, with local amounts in excess of 10 inches, falling in just over a four hour time period.

From NOAA’s Technical Paper No. 40 (SCS method) we can see that a 100-year 6-hour storm would be about a 7 inch event.

7

6

8

9

Areas impacted by this storm event were:

• Autauga County

• Elmore County

• Montgomery County

• Macon County

• Bullock County

Storm vs. flood, what is the difference?

• Oliver Creek• Sherwood Ditch• Jenkins Creek (2)• Baldwin Slough (2)• Three Mile Branch• Miller Creek

Following the May 7, 2009 flood event, the USGS collected data for the following streams:

Location of data collection sites

The Tools

Drainage area = 2.7 sq. mi.Computed peak flow = 4,880 cfsRunoff per square mile = 1,781 cfsmPublished Q500 (FEMA) = 3,500 cfs (Atlanta Highway – DA = 3.7 sq. mi)

Oliver Creek@

University Drive

Sherwood Ditch@

Sherwood Drive

Drainage area = 2.3 sq. mi.Computed peak flow = 6,170 cfsRunoff per square mile = 2,683 cfsmPublished Q500 (FEMA) = 4,987 cfs (At Mouth – DA = 2.8 sq. mi.)

Jenkins Creek@

Chantilly Pkwy

Drainage area = 7.1 sq. mi.Computed peak flow = 5,740 cfsRunoff per square mile = 808 cfsmPublished Q500 (FEMA) = 5,160 cfs (At CSX RR – DA = 7.3 sq. mi.)

Jenkins Creek@

I 65/US 80

Drainage area = 12.3 sq. mi.Computed peak flow = 9,700 cfsRunoff per square mile = 789 cfsmPublished Q500 (FEMA) = 10,480 cfs

Baldwin Slough@

McGee Road

Drainage area = 2.3 sq. mi.Computed peak flow = 5,720 cfsRunoff per square mile = 2,487 cfsmPublished Q500 (FEMA) = 3,430 cfs

Baldwin Slough@

Woodley Road

Drainage area = 4.6 sq. mi.Computed peak flow = 5,920 cfsRunoff per square mile =1,287 cfsmPublished Q500 (FEMA) = 6,090 cfs

Three Mile Branch@

Federal Drive

Drainage area = 8.1 sq. mi.Computed peak flow = 8,300 cfsRunoff per square mile =1,025 cfsmPublished Q100 (FEMA) = 8,209 cfs

Miller Creek@

I 65/US 80

Drainage area = 15.7 sq. mi.Computed peak flow = 5,220 cfsRunoff per square mile = 332 cfsmPublished Q50 (FEMA) = 6,730 cfs

Montgomery Runoff Curve for May 7, 2009 FloodC

FS

M

Drainage Area in sq. mi.

September, 2009 Atlanta flood

N.F. Peachtree Creek - 2000 cfsm (DA=1.42 sq. mi.)Butler Creek – 1878 cfsm (DA=3.6 sq. mi.)Allatoona Creek - 1177 cfsm (DA=14.1 sq.mi.) Pew Creek - 714 cfsm (DA=7.0 sq. mi.)Powder Springs Creek - 517 cfsm (DA=17.3 sq. mi.)Noonday Creek - 490 cfsm (DA=24.3 sq. mi.)Sope Creek - 325 cfsm (DA=29.2 sq. mi.)

May, 2010 Nashville flood

Locke Branch - 2222 cfsm (DA=0.81 sq. mi.)South Garrison Creek – 2137 cfsm (DA=0.51 sq. mi.)Slick Rock Creek - 2081 cfsm (DA=0.36 sq.mi.) White Oak Branch - 1962 cfsm (DA=0.26 sq. mi.)Kelley Creek - 1798 cfsm (DA=2.18 sq. mi.)Copperas Branch - 1519 cfsm (DA=1.62 sq. mi.)Richland Creek - 1296 cfsm (DA=24.3 sq. mi.)Browns Creek - 724 cfsm (DA=11.8 sq. mi.)

Sherwood Ditch - 2683 cfsm (DA=2.3 sq. mi.)Baldwin Slough – 2487 cfsm (DA=2.3 sq. mi.)Oliver Creek - 1781 cfsm (DA=2.7 sq.mi.) Baldwin Slough - 1287 cfsm (DA=4.6 sq. mi.)Three Mile Branch - 1025 cfsm (DA=8.1 sq. mi.)Jenkins Creek - 808 cfsm (DA=7.1 sq. mi.)Jenkins Creek - 789 cfsm (DA=12.3 sq. mi.)Miller Creek - 332 cfsm (DA=15.7 sq. mi.)

May, 2009 Montgomery flood

The Need: More Data!

New USGS gages: (Montgomery)Sherwood Ditch @ Sherwood Drive Baldwin Slough @ Woodley RoadOliver Creek @ University DriveJenkins Creek @ Chantilly PkwyThree Mile Branch @ Federal Drive

Questions ???