Everyone has questions about why we flooded after so many years without any danger. While we now know that Hurricane Ivan's aftermath brought about a "500-year flood" during which some amount of flooding was unavoidable, there are still measures we can take to help protect ourselves from so much damage in the future. As business owners or residents, whether or not you were directly affected by the flood, you are encouraged to attend a series of meetings we are sponsoring, so that as Carnegie boro and the surrounding municipalities and, ultimately, the watershed, formulate stormwater management plans, you are informed and involved in the process.
Topics covered at these meetings will include an overview of our watershed, the current state of the creek, flood control information, natural waterway management, stormwater management plans, and plenty of other topics to inform you about Chartiers Creek and in the Lower Chartiers Watershed. Information will be provided by local environmental scientists and engineers and organizations involved in studying Chartiers Creek in coordination with local stormwater management plan development.
The schedule of meetings and topics will be posted here in a week or two when we've coordinated topics and speakers. If you are interested in these meetings, please contact Carnegie Renaissance.
Now
that's a flash flood!
Information obtained from the
USGS recording unit in Carnegie showing flood levels on the day
of the flood with links to historical data.
Wingfield
Pines saves us from a complete disaster
A former golf course in Bridgeville
which was conserved instead of developed was filled with 180 million
cubic of creek water during the flood which otherwise would have
filled Chartiers Creek far beyond its capacity and caused an unimaginable
disaster.
I'm sure you'll be impressed
with the information--it may help to put in perspective just how
unusual this flood was and how proud we can all be that we weathered
it as well as we did. I have the link below, but first here is
a brief explanation and some interesting facts.
The USGS recording unit is "Allegheny County, Hydrologic
Unit 05030101, on left bank 100 ft downstream from Hammond Street
bridge..." In the Food Zone parking lot, right on the top
of the bank, you'll see a concrete block building; this is the
Hydrologic Unit that records the data. If you stand on the east
walkway of the Hammond Street Bridge facing toward Carnegie you'll
see it on the left, and if you look in the creek when the level
is normal, you'll see a little straight-line bump in the water
directly below the little building; this is the weir that takes
the measurements. (I used to think this was a telephone pole that
had fallen across the creek.)
Here are a few quick facts to impress others with:
--The highest point of depth and flow was 11:00 p.m. on Friday,
September 17.
--The creek's normal flow is about 18 inches; the maximum depth
at that time was 23.98 feet. I think 18 feet is flood stage. (Since
this is measured hourly the creek really did reach 25 feet, but
it is not documented by the equipment since it fell during the
hour.)
--The creek usually ambles along at about 220 cubic feet per second,
or 1,645 gallons per second; at the height of the flood it was
gushing along at 23,500 cubic feet per second, or 175,780 gallons
per second. As a comparison, American and Bridal Falls together
at Niagara flow at 150,000 gallons per second.
--The water rose 6 feet between 2:00 and 3:00 p.m., from approximately
6 feet to 12 feet (rounded off).
--Between noon and 6:00 p.m. it rose 18 feet, from about 3 feet
to 21 feet.
In researching historical data on the site:
http://nwis.waterdata.usgs.gov/pa/nwis/peak?s
ite_no=03085500&agency_cd=USGS&format=html
I didn't find anything like this. Flood Control in 1972 dredged
the creek to its current depth, but even looking at data from
1972 on the closest flow rates are half of what they were on Friday,
September 17.
The data are updated weekly, I think, and right now only display
up to Sunday; however, the creek still isn't down to normal. I
think we've redefined normal forever on this creek, though.
Here is the chart showing rates of water depth on September 17:
And here is a partial list of the flow rate data, hour by hour for September 17 and 18--the center column is the water depth in feet, the last column is the flow rate in cubic feet per second (multiply the cubic feet per second by 7.48 to get the gallons per second):
Gage Stream-
height, flow
Date / Time feet (ft³/s)
09/17/2004 00:00 1.59 220
09/17/2004 01:00 1.59 220
09/17/2004 02:00 1.59 220
09/17/2004 03:00 1.59 220
09/17/2004 04:00 1.59 220
09/17/2004 05:00 1.59 220
09/17/2004 06:00 1.60 224
09/17/2004 07:00 1.61 228
09/17/2004 08:00 1.65 249
09/17/2004 09:00 1.70 271
09/17/2004 10:00 1.80 325
09/17/2004 11:00 2.26 586
09/17/2004 12:00 2.98 1,060
09/17/2004 13:00 3.95 1,700
09/17/2004 14:00 6.14 3,360
09/17/2004 15:00 12.99 9,890
09/17/2004 16:00 17.41 14,599
09/17/2004 17:00 20.14 17,700
09/17/2004 18:00 21.66 19,500
09/17/2004 19:00 22.84 20,900
09/17/2004 20:00 24.08 22,400
09/17/2004 21:00 24.87 23,300
09/17/2004 22:00 24.95 23,400
09/17/2004 23:00 24.98 23,500
09/18/2004 00:00 24.88 23,400
09/18/2004 01:00 24.58 23,000
09/18/2004 02:00 24.34 22,700
09/18/2004 03:00 24.07 22,400
09/18/2004 04:00 23.88 22,100
09/18/2004 05:00 23.46 21,600
09/18/2004 06:00 23.05 21,100
09/18/2004 07:00 22.51 20,500
09/18/2004 08:00 21.88 19,700
09/18/2004 09:00 21.19 18,900
09/18/2004 10:00 20.31 17,900
09/18/2004 11:00 19.27 16,700
09/18/2004 12:00 18.17 15,400
09/18/2004 13:00 16.94 14,000
09/18/2004 14:00 15.70 12,700
09/18/2004 15:00 14.53 11,400
09/18/2004 16:00 13.37 10,300
09/18/2004 17:00 12.30 9,200
09/18/2004 18:00 11.28 8,179
09/18/2004 19:00 10.25 7,150
09/18/2004 20:00 9.18 6,080
09/18/2004 21:00 8.08 5,020
09/18/2004 22:00 6.97 4,030
09/18/2004 23:00 6.12 3,340
09/18/2004 23:15 5.81 3,100
09/18/2004 23:30 5.66 2,980
09/18/2004 23:45 5.53 2,870
09/19/2004 00:00 5.41 2,780
09/19/2004 00:15 5.30 2,690
Here is the page to view for
the information I have here:
http://nwis.waterdata.usgs.gov/pa/nwis/uv/?site_no=03085500&agency_cd=USGS
Since the default for data display is 7 days, you may need to
scroll to where it asks you how many days to show and change the
"7" to a higher number to be able to see the graph and
data.
Land
Conservation Reduces Ivan's Impact
The devastating flood of Chartiers Creek on September 17th could
have been even worse, if not for successful efforts to conserve
undeveloped floodplains in the valley over the past few years,
according to Roy Kraynyk, Executive Director of the Allegheny
Land Trust. The non-profit land conservancy’s Wingfield Pines
property is a good example of how land protection pays dividends.
Lake
Wingfield!
This 80-acre flood plain property, located just upstream from
Bridgeville, could have been paved and developed by now had it
not been for the Allegheny Land Trust’s 2002 purchase of
the property. Because it remained undeveloped, the grassy floodplain
meadow normally occupied by birds, deer, turkey and families out
for a hike or a walk with their dog, stored 180 million cubic
feet of flood water on Saturday, September 17th.
Nearly 15 feet of water covered the entire property. Water that would have otherwise roared down Chartiers Creek increasing the current’s velocity and the floodwater’s peak height. 180 million cubic feet of water is like a 550-foot high column of water the size of a football field. “Flood plains and their associated wetlands such that exist at Wingfield Pines act like giant sponges that absorb water during a flood and release it slowly as the water levels recede,” noted Allegheny Land Trust’s Executive Director, Roy Kraynyk.
Leaving flood plains undeveloped and steep slopes wooded can help reduce the frequency and intensity of flood events. Tree roots stabilize sloped land that is susceptible to landslides during heavy rains. Wooded slopes, floodplains and wetlands effectively absorb and retain water reducing the amount that enters rivers, streams and tributaries. Encouraging development away from these areas can also prevent the substantial loss of property. It can be more cost effective to protect these natural systems than it is to rebuild homes and businesses each time property is damaged.
Bob Hedin of Hedin Environmental who is working with the Trust to design a system of ponds to treat abandon mine drainage visited the property early Saturday morning. “At the peak of the flood on Saturday morning, Wingfield Pines provided a second primary flow channel for Chartiers Creek. This slowed the velocity of the Creek’s flow and potentially lessened the elevation of the flood crest downstream,” commented Hedin. “I don't know yet how much lower the crest was, but for property owners downstream inches mattered.”
Allegheny Land Trust has dedicated Wingfield Pines as forever open space. Home or business owners, who may have occupied the property by now were it not for the Trust’s purchase, would have been devastated and likely be seeking public funds or making insurance claims to restore flood-damaged properties.
For more information, please send us an e-mail or call the Trust at 412-749-4882.
Wingfield Pines Flooding -- Last modified: 09/24/2004 11:20:05
Created by Site Administrator, mail@alleghenylandtrust.org
All original material copyright © 2002-2004 by Allegheny
Land Trust
For the original article and to visit the Allegheny Land Trust's website: http://www.alleghenylandtrust.org/WingfieldFlooding.html