Floods - Lecture 1 What Causes Flooding?

Transcription

Schultz House,
Johnstown, Pennsylvania
1889
Floods Lecture 1
McCullough, David, 1968,
The Johnstown Flood:
New York, Simon &
Schuster, Inc., 302 p
What Causes Flooding?
• What Causes High
Water?
• What Causes
Damage When
There is High
Water?
Human Role
Floodplain Encroachment
People & Structures in Harm’s Way
Worsens Floods Downstream
Dams
Dam Failures
Levees
Worsens Floods Downstream
Levee Failure Increases Flow Energy
Land-Use Changes
Changes in Runoff Coefficients
1
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!
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”
Risin
g Lim
b
Crest
Fa
llin
g
Li
m
b
New
“Base Flow”
0 cfs
2
ea
ed
r
we
d
ks
in
yl
n
Real-Time Flow Links foraFlood Chasers &
m
River Rats (beware some
oo links have "decayed")
t
e
us
ca
http://www.geo.wvu.edu/~kite/welcome.htm
e
b
06
20
in
de
s li
d
Hi
NWSFO PITTSBURGH PA
HYDROLOGIC SERVICES AREA
Hydrology/River Products Web Page
http://www.erh.noaa.gov/er/pit/hydro.htm
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
3
Note Vertical Axis Change
Deckers CreekPeak:Stage
Early a.m. 23rd
Guyandotte River Hydrograph July
2001
4
Approaches to Flood “Prediction”
National Weather Service
• Flood Watch, Flood Warning
• Based on
Flow in Steams
Antecedent 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.htm
Old Data: http://www.afws.net/search1.htm
Last Updated: February 18, 2000 at 8:00 PM EST
Data for Monongalia County, West Virginia
Crossroads Sw
Jakes Run
Dents Run
Pleasant Hill Cm
Strawn Lake
ID 15MIN
3850 0.08
3851 0.08
3852 0.08
3853
3854 0.08
30MIN
1HR
3HR
6HR
12HR 24HR
0.20 0.36 0.60 0.64 1.72 1.96
0.20 0.32 0.56 0.56 1.68 1.92
0.20 0.28 0.48 0.48 0.48 0.52
0.12 0.24 0.44 0.48 1.96 2.16
NOAA
Rainfall Gage
Data
Total 37 Hour
Rainfall: Ending
19 Feb 2000
Max: 6.05“
http://www.nws.noaa.
gov/er/iln/0218.gif
5
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, PA
1043 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 THU
OHIO 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/
OHZ067 0.6/ 1.1/ 1.3/ 1.6/
OHZ076 0.6/ 1.1/ 1.3/ 1.7/
OHZ075 0.5/ 1.0/ 1.3/ 1.6/
OHZ086 0.5/ 1.0/ 1.2/ 1.6/
OHZ083 0.5/ 1.0/ 1.2/ 1.5/
OHZ087 0.5/ 1.0/ 1.2/ 1.6/
OHZ085 0.5/ 1.0/ 1.3/ 1.7/
OHZ084 0.5/ 1.0/ 1.2/ 1.6/
2.1 :PERRY CO
2.1 :MORGAN CO
2.2 :WASHINGTON CO
2.1 :ATHENS CO
2.1 :GALLIA CO
2.0 :JACKSON CO
2.1 :LAWRENCE CO
2.2 :MEIGS CO
2.1 :VINTON CO
6
Other Approaches to Floods
Rational Method
(The Ultimate Open System)
Qpk = CIA
Qpk =
C =
Peak Flow (cfs)
Runoff Coefficient
[0.1 (sandy lawns) to 0.95 (asphalt)]
I
A
=
Rainfall Intensity (ft/hr)
=
Drainage Area (ft2)
Unit Hydrograph
Rainfall
1 inch
Discharge
Risin
g Lim
b
Crest
Fa
llin
g
Li
m
b
“Base Flow”
New
“Base Flow”
0 cfs
Hydrograph:
Base-Flow Separation
Discharge
Risin
g Lim
b
Crest
“Base Flow”
Fa
lli
ng
Li
m
b
New
“Base Flow”
0 cfs
7
“Separated” Unit
Hydrograph
Rainfall
1 inch
Fa
lli
ng
Ris
ing
L
Discharge
“X”
imb
Crest
Li
m
b
0 cfs
Rainfall
Crest
“2X”
“X”
g
llin
Fa
Discharge
m
Li
b
Rising Lim
b
2 inches
Unit Hydrograph
for 2 Inch Rainfall
0 cfs
Rainfall
Crest
m
Li
b
“Base Flow”
“2X”
g
llin
Fa
Discharge
Rising Lim
b
2 inches
2 X Unit Hydrograph
+ Base Flow
0 cfs
8
Synthetic
Hydrograph for
2 Inch Rainfall &
Given Base Flow
Rainfall
Discharge
“Base Flow”
0 cfs
Cumulative Runoff
Time-Area Method of Runoff Modeling
15 min
30 min
45 min
0 min
30 min
60 min
Time
Prediction from Gage Records
Gumbel Plot
Log-Pearson Type III
Used for High Flows or Low Flows
Annual Series: Extremes for Each Year Only
vs.
Partial Duration: All Events Beyond Threshold
9
n
io
at
l
o
ap
tr
?
x
E
Flood
Frequency
n
io
at
l
o
rp
te
In
200
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
05/31/1985
28600
11/05/1985 170000
01/19/1987
16500
01/20/1988
16600
03/06/1989
29100
GageAtPeak
12.68
24.30
9.87
9.90
12.62
Rank
#3
#1
#2
10
Cheat R. @ Parsons 1985-1989 Partial Duration Series
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Date
Discharge
05/31/1985
28600
02/25/1985
23100
03/12/1985
17500
07/10/1985
19900
11/05/1985 170000
11/29/1985
39600
02/04/1986
19200
03/11/1986
18800
03/15/1986
35800
07/02/1986
17000
01/19/1987
16500
01/20/1988
16600
05/06/1988
16500
03/06/1989
29100
08/23/1989
21100
GageAtPeak
12.68
11.45
10.15
10.72
24.30
17.68
13.43
13.33
17.05
12.87
9.87
9.90
9.88
12.62
11.02
Rank
#1
#2
#3
Station 03069500 Cheat R. @
Parsons Annual Flood Series
Next
Slide
•
•
•
•
•
•
•
•
{
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
Cheat R. @ Parsons 1995-1996 Partial Duration Series
•
•
•
•
•
•
•
•
•
•
•
•
•
Date
Discharge
08/06/1995
19700
05/14/1995
18600
01/19/1996
90100
02/28/1996
23100
05/05/1996
18200
05/06/1996
23300
05/17/1996
50000
05/28/1996
17800
07/19/1996
52500
07/31/1996
50000
08/13/1996
22000
09/06/1996
46600
GageAtPeak
10.94 1995 Annual Flood
10.72
19.84 1996 Annual Flood
11.39 >1995 Annual Flood
10.33
10.25
11
Annual Variations in Floods
USGS Data
Annual Variations in Floods
12
Cosumnes River, CA, 1997
Box 10.02.f3
Recurrence Interval (Tr)
Tr = 1/p = (n+1)/m
p = Probability
n = Number of Years in Record
m = Rank of Event
13
Light Yellow Background
Denotes 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
Precipitated
Moisture
tu
Sa
d
te
ra
r
Ai
Unsaturated
Air
Causes of Precipitation
14
Thiessen Method for Average Rain
Rainfall Rate-Duration-Frequency
15
Plant Available Water versus Texture
Plant Response to Soil-Water Content
Plants do not reduce flooding when it is very dry or very wet!
Seasonal Soil Water Balance in Ohio
Fig. 3.23
16
U.S. Annual Precipitation
http://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 Survey
which 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.
17
Moisture Sources
for “Lower 48”
Air-Mass
Interactions
by Season
Precipitable Moisture in the Lower Atmosphere
Mean Annual
Mean July
18
Figure 2.20
Prediction
by Month
http://streams.osu.edu/book/PowerPoints/chapter2.ppt#284,33,Slide 33
Number of Days
With
Thunderstorms
19
Tropical
Cyclone
Tracks
& Probability
Regional Flood
Seasons
Qmax Week by Week: All Events
160
160
WEEKLY SUMMARY OF PEAK FLOWS IN THE OHIO
RIVER BASIN
140
Frequency
120
120
100
80
80
60
40
40
20
0
0
Ja
Ja n 1n 7
2
F e 2-2
b 8
12
M M ar 18
ar
5
2 6 -1 1
-A
Ap pr
r1 1
M 6M ay 22
ay 7
28 -13
-J
Ju un
n 3
18
-2
Ju Jul 4
l 3 90- 15
A
Au u g
g 5
2
Se 0-2
p 6
10
O 16
c
O t 1ct 7
2
No 2-2
v 8
12
De - 1 8
De c 3
c 2 -9
431
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
20
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
Frequency
20
0
Month of Qmax 10-100 km2 Basins
70
Frequency
*
*
*
*
*
*
0
21
Month of Qmax 1000-10,000 km2 Basins
Frequency
140
0
Month of Qmax >100,000 km2 Basins
Frequency
10
0
Jan 1937
Total Precip.
as % of
“Normal”
22
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
23
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.ltrr.arizona.edu/~sstgeorg/research_files/image005.jpg.
www.mvp-wc.usace.army.mil/org/rrn/flood97/photos/S2apr24.jpg
24
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
25
What Happened in
West Virginia on
26 February 1972?
Buffalo Creek Flood
wvgazette.com/static/series/
wvgazette.com/static/series/
buffalocreek/index.html
http://wvgazette.com/static/series/buffalocreek/index.html
wvgazette.com/static/series/buffalocreek/index.html
26
125 Names
What Went Wrong
by Margado and Ward, 1997
• http://wvgazette.com/st
atic/series/buffalocreek
/dam/dam2.html
27
The Buffalo Creek Flood: an Act of Man
call 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,
Pennsylvania
1889
28

Floods - Lecture 1 What Causes Flooding?

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