1
Floods -Lecture 1
Schultz House,Johnstown, Pennsylvania
1889
McCullough, David, 1968, The Johnstown Flood: New York, Simon & Schuster, Inc., 302 p
What Causes Flooding?
• What Causes High Water?
• What Causes Damage WhenThere is High Water?
Human RoleFloodplain Encroachment
People & Structures in Harm’s WayWorsens Floods Downstream
Dams Dam Failures
LeveesWorsens Floods DownstreamLevee Failure Increases Flow Energy
Land-Use ChangesChanges in Runoff Coefficients
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Flood Problems are People Problems
Ignorance of Rivers and Streams
Poor (Selective?) Memory of Historic Floods
Arrogance of Our Ability to Overcome Nature
Greed to Exploit Floodplain Property
Lack of Zoning and Planning
Sooner or later, the river exerts authority over its entire domain!
Sooner or later, the river exerts authority over its entire domain!
Review: Flood Frequency Terms
• Stage = Height of Water (Above Arbitrary Datum)
• Discharge = Volume/Time (cfs, cms)• Recurrence Interval
– Average Time Between Events of a Given Size or larger
Hydrograph
Discharge
“Base Flow”New
“Base Flow”
Crest
Ris
ing
Lim
b
Falling Limb
0 cfs
3
Real-Time Flow Links for Flood Chasers & River Rats (beware some links have "decayed")
http://www.geo.wvu.edu/~kite/welcome.htm
Hid slide in 2006 because too many lin
ks were dead
http://www.erh.noaa.gov/er/pit/hydro.htm
NWSFO PITTSBURGH PA HYDROLOGIC SERVICES AREA Hydrology/River Products Web Page
US Geological Survey Real-Time Stream Flow Info
• http://water.usgs.gov/cgi-bin/daily_flow?wv
– USGS 03206000 OHIO RIVER AT HUNTINGTON, WV– USGS 01605500 SOUTH BRANCH POTOMAC AT FRANKLIN, WV– USGS 03200500 COAL RIVER AT TORNADO, WV– USGS 03202400 GUYANDOTTE RIVER NEAR BAILEYSVILLE, WV– USGS 03204000 GUYANDOTTE RIVER AT BRANCHLAND, WV
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Deckers Creek StagePeak: Early a.m. 23rd
Not
e V
ertic
al A
xis
Cha
nge
Guyandotte River Hydrograph July 2001
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Approaches to Flood “Prediction”National Weather Service
• Flood Watch, Flood Warning• Based on
Flow in SteamsAntecedent Conditions: Ground
Saturation, etc. Current Conditions: Precipitable
Moisture Weather Forecast
IFLOWS: West Virginia Automated Flood Warning System (AFWS)
http://198.200.163.197/data/wv/wvdata.htmOld Data: http://www.afws.net/search1.htm
Last Updated: February 18, 2000 at 8:00 PM EST
Data for Monongalia County, West Virginia
ID 15MIN 30MIN 1HR 3HR 6HR 12HR 24HRCrossroads Sw 3850 0.08 0.20 0.36 0.60 0.64 1.72 1.96Jakes Run 3851 0.08 0.20 0.32 0.56 0.56 1.68 1.92Dents Run 3852 0.08 0.20 0.28 0.48 0.48 0.48 0.52Pleasant Hill Cm 3853 - - - - - - -Strawn Lake 3854 0.08 0.12 0.24 0.44 0.48 1.96 2.16
NOAARainfall Gage
DataTotal 37 Hour Rainfall: Ending 19 Feb 2000Max: 6.05“
http://www.nws.noaa.gov/er/iln/0218.gif
6
NWS Predictions are Mostly Empirical
Computer Modeling(+ Intuition & Experience)
Daily Forecasts Ohio River Basin:Dead Link
http://www.nws.noaa.gov/er/iln/rvs.htm
Try http://www.erh.noaa.gov/er/pit/hydro.htm
RIVER FORECASTS - STAGE NATIONAL WEATHER SERVICE PITTSBURGH, PA1043 AM EST MON FEB 21 2000
RIVER FORECASTS ARE BASED ON A FORECAST OF NO PRECIPITATION IN THE NEXT 24 HOURS.
FLD OBSERVED FORECAST 7AM LOCATION STG STG 7AM TUE WED THUOHIO RIVER
PITTSBURGH 25 16.7 16.7 16.6 16.6
PIKE ISLAND L/D 37 24.5 18.3 18.0 18.1
WHEELING 36 24.6 18.3 17.9 18.0
ZONE FLASH FLOOD GUIDANCE NATIONAL WEATHER SERVICE
OHIO RIVER FORECAST CENTER...WILMINGTON OH ISSUED 0144 PM EST FRI FEB 18 2000
: AVERAGE RAINFALL IN INCHES NEEDED TO BEGIN FLOODING : STEEP TERRAIN CAN GREATLY REDUCE APPARENT INDEX :IDENT 1HR 3HR 6HR 12HR 24HR ZONE NAME :======= ==== ==== ==== ==== ==== ==================== : NWSFO CHARLESTON OHZ066 0.6/ 1.0/ 1.3/ 1.6/ 2.1 :PERRY CO OHZ067 0.6/ 1.1/ 1.3/ 1.6/ 2.1 :MORGAN CO OHZ076 0.6/ 1.1/ 1.3/ 1.7/ 2.2 :WASHINGTON CO OHZ075 0.5/ 1.0/ 1.3/ 1.6/ 2.1 :ATHENS CO OHZ086 0.5/ 1.0/ 1.2/ 1.6/ 2.1 :GALLIA CO OHZ083 0.5/ 1.0/ 1.2/ 1.5/ 2.0 :JACKSON CO OHZ087 0.5/ 1.0/ 1.2/ 1.6/ 2.1 :LAWRENCE CO OHZ085 0.5/ 1.0/ 1.3/ 1.7/ 2.2 :MEIGS CO OHZ084 0.5/ 1.0/ 1.2/ 1.6/ 2.1 :VINTON CO
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Other Approaches to Floods
Rational Method (The Ultimate Open System)
Qpk = CIA
Qpk = Peak Flow (cfs)
C = Runoff Coefficient [0.1 (sandy lawns) to 0.95 (asphalt)]
I = Rainfall Intensity (ft/hr)
A = Drainage Area (ft2)
Unit HydrographRainfall
Discharge
1 inch
“Base Flow”New
“Base Flow”
Crest
Ris
ing
Lim
b
Falling Limb
0 cfs
Hydrograph:Base-Flow Separation
Discharge
“Base Flow”
New “Base Flow”R
isin
g Li
mb
Falling Limb
Crest
0 cfs
8
“Separated” UnitHydrographRainfall
1 inch
“X”Crest
Discharge
Risi
ng L
imb Falling Limb
0 cfs
Unit Hydrograph for 2 Inch Rainfall
Rainfall
Discharge
“2X”2 inchesCrest
Ris
ing
Lim
b Falling Limb
“X”
0 cfs
2 X Unit Hydrograph+ Base Flow
Rainfall
Discharge
“2X”2 inchesCrest
Ris
ing
Lim
b Falling Limb
“Base Flow”
0 cfs
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Synthetic Hydrograph for2 Inch Rainfall & Given Base Flow
Rainfall
Discharge
“Base Flow”
0 cfs
Time-Area Method of Runoff Modeling
Time
Cum
ulat
ive
Run
off
15 min 45 min30 min 0 min 60 min30 min
Prediction from Gage Records
Gumbel PlotLog-Pearson Type III
Used for High Flows or Low Flows
Annual Series: Extremes for Each Year Only vs.
Partial Duration: All Events Beyond Threshold
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Flood Frequency
Extrap
olation
Extrap
olation
200
?
Interpolat
ion
Interpolat
ion
Flood Frequency
• Recurrence Interval: Like Rolling Dice
• 100 year flood - BAD TERM• 1 percent flood - Better
Cheat R. @ Parsons 1985-1989 Annual Flood Series
• Date Discharge GageAtPeak Rank• 05/31/1985 28600 12.68 # 3 • 11/05/1985 170000 24.30 # 1• 01/19/1987 16500 9.87 • 01/20/1988 16600 9.90 • 03/06/1989 29100 12.62 # 2
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Cheat R. @ Parsons 1985-1989 Partial Duration Series• Date Discharge GageAtPeak Rank• 05/31/1985 28600 12.68 • 02/25/1985 23100 11.45 • 03/12/1985 17500 10.15 • 07/10/1985 19900 10.72 • 11/05/1985 170000 24.30 # 1• 11/29/1985 39600 17.68 # 2• 02/04/1986 19200 13.43 • 03/11/1986 18800 13.33 • 03/15/1986 35800 17.05 # 3• 07/02/1986 17000 12.87 • 01/19/1987 16500 9.87 • 01/20/1988 16600 9.90 • 05/06/1988 16500 9.88 • 03/06/1989 29100 12.62 • 08/23/1989 21100 11.02
Station 03069500 Cheat R. @ Parsons Annual Flood Series• Date Discharge GageAtPeak• 05/26/1990 42500 14.79 • 12/03/1991 30600 12.93 • 07/27/1992 26900 12.31 • 04/01/1993 22300 11.47 • 02/09/1994 78300 18.85 • 08/06/1995 19700 10.94 • 01/19/1996 90100 19.84 {Next
Slide
Cheat R. @ Parsons 1995-1996 Partial Duration Series
• Date Discharge GageAtPeak• 08/06/1995 19700 10.94 1995 Annual Flood• 05/14/1995 18600 10.72• 01/19/1996 90100 19.84 1996 Annual Flood • 02/28/1996 23100 11.39 >1995 Annual Flood• 05/05/1996 18200 10.33 • 05/06/1996 23300 11.43 >1995 Annual Flood • 05/17/1996 50000 15.71 >1995 Annual Flood• 05/28/1996 17800 10.25• 07/19/1996 52500 16.06 >1995 Annual Flood • 07/31/1996 50000 15.72 >1995 Annual Flood • 08/13/1996 22000 11.17 >1995 Annual Flood • 09/06/1996 46600 15.23 >1995 Annual Flood
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Annual Variations in FloodsUSGS Data
Annual Variations in Floods
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Cosumnes River, CA, 1997
Box 10.02.f3
Recurrence Interval (Tr)
Tr = 1/p = (n+1)/m
p = Probabilityn = Number of Years in Recordm = Rank of Event
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Light Yellow BackgroundDenotes Flood Hydrology Slides
from
Ward, Andy D. and Trimble, Stanley W., 2004, Environmental Hydrology, 2nd Edition, Lewis Publishers, 462 p.
• Source: http://streams.osu.edu/book/lectures.php
Air Saturation
Unsaturated Air
Saturated AirPrecipitated
Moisture
Causes of Precipitation
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Thiessen Method for Average Rain
Rainfall Rate-Duration-Frequency
Rainfall Rate-Duration-Frequency
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Plant Available Water versus Texture
Plant Response to Soil-Water Content
Plants do not reduce flooding when it is very dry or very wet!
Fig. 3.23
Seasonal Soil Water Balance in Ohio
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U.S. Annual Precipitationhttp://streams.osu.edu/book/PowerPoints/chapter2.ppt#263,9,Slide 9
Annual Pan Evaporation in the USA
Flood Climatology
Next Five Figures are from
Some Perspectives on Climate and Floods in the Southwestern U.S.U.S. Geological Surveywhich is abstracted primarily from:
Hirschboeck, K.K., 1991, Climate and floods, in Paulson, R.W., Chase, E.B., Roberts, R.S., and Moody, D.W., Compilers, National Water Summary 1988-89--Hydrologic Events and Floods and Droughts: U.S. Geological Survey Water-Supply Paper 2375, p. 99-104.
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Moisture Sources for “Lower 48”
Air-Mass Interactions by Season
Precipitable Moisture in the Lower Atmosphere
Mean Annual Mean July
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Figure 2.20
Rainfall Rate-Duration-Frequency
Prediction by Month
http://streams.osu.edu/book/PowerPoints/chapter2.ppt#284,33,Slide 33
Number of DaysWith
Thunderstorms
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Tropical Cyclone Tracks
& Probability
Regional Flood Seasons
WEEKLY SUMMARY OF PEAK FLOWS IN THE OHIO RIVER BASIN
0
20
40
60
80
100
120
140
160
Jan 1-
7
Jan 22
-28
Feb 12
-18
Mar
5-11
Mar
26-A
pr 1
Apr 16-2
2
May
7-13
May
28-Ju
n 3
Jun 18
-24
Jul 9
-15
Jul 3
0-Aug 5
Aug 20-2
6
Sep 10
-16
Oct 1-7
Oct 22
-28
Nov 12
-18
Dec 3-
9
Dec 24
-31Jan Dec
Freq
uenc
y
0
40
80
120
160
Mar May Jul OctJunFeb Apr Aug Sep Nov
Qmax Week by Week: All Events
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Weekly Qmax Summary
* March, Week 2: 8% of Qmax Events* March 1- April 10: ~28% of Qmax Events* Late January “Thaw”: Above Normal * Late Spring to Mid-Summer: Above Normal * October, Week 4: None of 1832 Qmax Events* Individual Events Matter
Month of Qmax <1.0 km2 Basins
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Freq
uenc
y
20
0
Month of Qmax 10-100 km2 Basins
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Freq
uenc
y
70
0
22
Month of Qmax 1000-10,000 km2 Basins
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Freq
uenc
y
140
0
Month of Qmax >100,000 km2 Basins
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Freq
uenc
y
10
0
Jan 1937Total Precip.
as % of “Normal”
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Jan 1937: Portsmouth, Ohio
Jan 1937: 60 ft Floodwall Topped, Portsmouth, Ohio
There are floods and there are floods!
• Variability Contolled by – Basin Size – Topography & Other Basin Characteristics
• Urbanization– Climate
• Flash Floods vs. 1993 Mississippi River
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1993 “Flood of the Century”
St. Louis Area, 1993
Red River Flood North Dakota & Manitoba
April 1997
ccrs.nrcan.gc.ca/radar/spaceborne/radarsat1/action/canada/redfld_e.php
www.mvp-wc.usace.army.mil/org/rrn/flood97/photos/S2apr24.jpg
www.ltrr.arizona.edu/~sstgeorg/research_files/image005.jpg.
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Flashy Streams of the Colorado Front Range
& Rocky Mountains
Big Thompson Canyon Flood, 1976
Big Thompson Canyon Flood, 1976
144 Dead & Missing, $35 Million Damage
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wvgazette.comwvgazette.com/static/series//static/series/buffalocreek/index.htmlbuffalocreek/index.html
What Happened inWest Virginia on
26 February 1972?
Buffalo Creek Flood
http://wvgazette.com/static/series/buffalocreek/index.html
wvgazette.com/static/series/buffalocreek/index.html
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wvgazette.com/static/series/buffalocreek/index.html
wvgazette.com/static/series/buffalocreek/index.htmlwvgazette.com/static/series/buffalocreek/index.html
125 Names
What Went Wrongby Margado and Ward, 1997
• http://wvgazette.com/static/series/buffalocreek/dam/dam2.html
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The Buffalo Creek Flood: an Act of Mancall nos. VHS video: WVU-AVL VT3610, DVD: MEDIA DV1359 AV LIB
• Where (and what) is Logan County?• What is an “Act of God”?
– Precipitation Amounts in Feb 1972?• Who was responsible? Who provided Relief?• What were the dams built from?
– Slate?• Why were the “dams” built?• What was Pittston Coal’s response to the flood?• What was the State government response to the flood?
– Gov. Moore’s “lame duck” resolution w/ company• What was the citizens response?
– $100,000,000 Class Action Suit, settled for >$13,000,000 • What were conditions 2 years later?• “Buffalo Creek Revisited”(1985)• What are general lessons to be learned?
Other
• Ground-breaking Class Action Suit• Lessons for “FEMA”
– Relocation strategy– Psychological Disorders
Floods -Lecture 2
Schultz House,Johnstown,
Pennsylvania1889