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

2

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

4

Deckers Creek StagePeak: Early a.m. 23rd

Not

e V

ertic

al A

xis

Cha

nge

Guyandotte River Hydrograph July 2001

5

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

7

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

9

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

10

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

11

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

12

Annual Variations in FloodsUSGS Data

Annual Variations in Floods

13

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

14

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

15

Thiessen Method for Average Rain

Rainfall Rate-Duration-Frequency

Rainfall Rate-Duration-Frequency

16

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

17

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.

18

Moisture Sources for “Lower 48”

Air-Mass Interactions by Season

Precipitable Moisture in the Lower Atmosphere

Mean Annual Mean July

19

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

20

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

21

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”

23

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

24

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.

25

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

26

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

27

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

28

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