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Flooding – understanding the human dimension Professor Edmund Penning-Rowsell, Middlesex University
Somerset: Winter 2014
“Flooding” – 12 mentions
“Flooding” – 13 mentions
“Flooding” – 26 mentions !!
This is something you might just need to learn …..
So, listen carefully …..
Somerset: Winter 2014 Floods
Impacts Responses
Somerset: Winter 2014
Floods:
Physical drivers
Human dimensions
Management of floods and
flood risk
• Floods from rivers
• Floods from the sea
• Floods in cities from extreme rainfall
• Floods direct from the land: “surface water flooding”
Smalls floods
Big floods
Rare floods
Flash floods
Deep floods
High velocity floods
Contaminated
floodwaters
Damaging floods
(big impacts)
Disruptive floods
Dangerous floods
Types of Floods
£5,000
£22,000
£31,000
£38,000
£44,000
We know a great deal about the
economic damage caused by floods…. Impact 1
But the economic damage caused by
floods is only part of the story ….
Plus:
Impact 2
Evacuation:
50% of those
with flood water
> 30cm are not
back in their
homes inside 30
days
Impact 3: Immediate self-reported physical health effects (1998/2000)
Immediate physical health
effects
Percentage reporting the effect [N = 71]
Shock 58
Colds, coughs, ‘flu, sore throats
41
Headaches 30
From exposure to contaminants
22
Injuries due to over-exertion 17
Skin irritations 15 Injuries from being knocked over by flood waters
7
Other 15
None of the above 18
Floods and
health impacts:
a 4 year study
after the 1998
floods
Impact 3: Self-reported physical health effects in the aftermath of flooding
Physical health effects in
aftermath of flooding
Percentage reporting the
effect [N = 71]
Stiffness in joints 23
Respiratory illness 21
Gastro-intestinal illness 20 Weight loss 20
Skin irritations 16
Muscle cramps 16
High blood pressure 14
Sprains and strains 14
Cuts and bruises 11 Heart problems 6
Other 28
None of the above 36
Impact 3: Self-reported mental healtheffects of the flooding
Mental health effects ofthe flooding
Percentagereporting
[N = 71]
Anxiety when rains 80
Increased stress levels 67
Depression (mild to severe) 56
Sleeping problems 51
Lethargy/lack of energy 39
Flashbacks to the flood 36
Mood swings/bad moods 35
Difficulty concentrating on tasks 35
Increased tension in relationships 31
Panic attacks 27
Anger/tantrums 24
Increased use of alcohol/drugs 18
Nightmares 18
Thoughts of suicide 9
Other 6
None of the above 6
Flood
0 1 2 years
Psychological
impacts
Physical
impacts ??
Impact 3: Health and floods: The time
line of impacts
Up to
80%
< 60%
So what can we do to reduce the
flood risk? Types of responses
Engineering
measures:
Keeping the water
away or reducing
flood probability
Dams/reservoirs
Flood walls/levees
Flood gates
Dredging channels
By-pass channels
Non-engineering &
‘human’ measures
Reducing
vulnerability and
likely damages
Controlling floodplain
development
Warning systems
Emergency response
Insurance
So what can we do to reduce the
flood risk? Two specific responses
Engineering
measures:
Keeping the water
away or reducing
flood probability
Dams/reservoirs
Flood walls/levees
Flood gates
Dredging channels
By-pass channels (UK)
Non-engineering &
‘human’ measures
Reducing
vulnerability and
likely damages
Controlling floodplain
development
Warning systems
Emergency response
Insurance (Bangladesh)
The river Thames catchment
London
Floods
July 2007
rainfall: the
physical
driver of that
flood event
Surge tides
RESPONSE No. 1: The Maidenhead and the “Jubilee River” flood by-pass channel
The river Thames catchment
London
So what does a bypass
channel do?
1. Takes flood water from the main
channel, just like a by-pass road takes
road traffic around a town
2. Reduces flood risk from the main
channel in the towns: Maidenhead;
Windsor; Eton
3. Re-connects with the main channel
downstream
1
2
3 2
RESPONSE NO. 2
The Thames Barrier in
London
North
Sea
Surge tides
Raised gate
Raised gate
Thames Barrier closures each year:
the response to flood risk
Protecting 1.25 million people, 58 tube
stations, 16 hospitals, 8 power stations
and 400 schools, etc.
Global-mean sea-level rise IPCC Third Assessment Report AR5 (2013)
Representative Concentration Pathways
(RCPs) are four greenhouse gas concentration
(not emissions) trajectories adopted by the
IPCC for its fifth Assessment Report (AR5).
Surges would come
on top of this
Source: UKCIP02 Climate Change Scenarios (funded by DEFRA, produced by Tyndall and Hadley Centres for UKCIP)
The 5-year surge height increase (m) for the 2080s
Low emission scenario: climate change
Medium-high emission scenario
The 5-year surge height increase (m) for the 2080s
Source: UKCIP02 Climate Change Scenarios (funded by DEFRA, produced by Tyndall and Hadley Centres for UKCIP)
The 5-year surge height increase (m) for the 2080s
Source: UKCIP02 Climate Change Scenarios (funded by DEFRA, produced by Tyndall and Hadley Centres for UKCIP)
High emission scenario 1.4 metres surge
So: 0.2 + 1.4 = 1.6
metres. This is
getting serious….
Floods are dangerous: Glasgow 2002
Impact 4
‘Flume’ experiments: stunt
man and varying flood
depths and velocities:
standing; walking
across stream; walking
upstream
Courtesy BBC ‘999’
Floods are dangerous
‘Flume’ experiments: stunt
man and varying flood
depths and velocities:
standing; walking
across stream; walking
upstream
Courtesy BBC ‘999’ BBC 999 DVD
Velocity
Depth
Upstream
Test: Gate
opened
0.46m; man
fell over at
3.0m/sec and
0.25m depth.
Time
Stunt man: Walking upstream
Dummy run
3.0 m/sec
0.25m depth
Gate
open
0.46m
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 0.5 1 1.5 2 2.5 3 3.5
Velocity (m/sec)
De
pth
of f
loo
d w
ate
r (
m) Hazard zone
'Safe' zone
Standing and walking experiments: Summary results
Experimental
results
Jonkman, S.N. and Penning-Rowsell, E.C. (2008). Human Instability in Flood Flows. Journal of the
American Water Resources Association 44(4):1-11. DOI: 10.1111 ⁄ j.1752-1688.2008.00217.x
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0 0.5 1 1.5 2 2.5 3 3.5
De
pth
of f
loo
d w
ate
r (
m)
Velocity (m/sec)
Hazard zone
'Safe' zone
Safer zone
Hazard zone
0
5000
10000
15000
20000
25000
30000
35000
Ve
ne
zue
la,
Flas
h f
loo
d
Ind
ia, G
en
era
lFl
oo
d
Ch
ina
P R
ep
,G
en
eral
flo
od
Ch
ina
P R
ep
,G
en
eral
flo
od
Hai
ti, G
en
era
lfl
oo
d
Ban
glad
esh
, --
Som
alia
,G
en
eral
flo
od
Ban
glad
esh
,G
en
eral
flo
od
Ind
ia, -
-
Ch
ina
P R
ep
, --
Inclusion criteria:
• 10 or more people reported killed
• 100 people reported affected
• A call for international assistance
• Declaration of a state of emergency
Floods are dangerous: just the last 25 years
Liv
es l
ost
in f
loo
ds
c. 30,000
deaths in
Venezuela
flash flood
(1999)
c. 30,000
deaths in
Venezuela
flash flood
(1999):
Rainfall =
91 cm (36
inches) in
2.1 days
Physical ...
Human …
Caraballeda, Vargas state, Venezuela
Bangladesh United Kingdom
Area 57,000 sqr miles 94,000 sqr miles
Population 160 million 65 million
People per sqr mile 2,800 690
Bangladesh: the flood-prone delta in the
catchments of the Ganges and Brahmaputra
Emergency response
Bangladesh
Drivers
Bangladesh
The summer monsoon Dhaka has 185
cm (73 in) of
rainfall between
May and
September.
Dhaka
The monsoon rain
36 cm
Impacts
RESPONSE:
embankments
RESPONSE:
embankments
Small scale regular
flooding in Bangladesh is
required to grow rice, so
natural flooding replaces
the requirement of
artificial irrigation.
Flood can remove salt
deposited on fields from
high rates of
evaporation, preventing
the land from becoming
infertile.
IMPACTS: POSITIVE
PHYSICAL : Tidal waves up to five
metres high and surges up
to 6 metres.
Breaching coastal and river
embankments, flooding low-
lying areas and causing
extensive physical damage
destruction.
On 15 November
2007, Cyclone Sidr
struck the south-
west coast of
Bangladesh with
winds up to 150
miles per hour.
Tropical
cyclones
IMPACTS: NEGATIVE
15 November 2007: Some 2.3
million households were affected
to some degree by Cyclone Sidr.
About one million were seriously
affected.
The number of deaths is
estimated at 3,406 … and over
55,000 people sustaining
physical injuries.:
RESPONSE: emergency response
Evacuation to ‘safe
havens’ in Cyclone
shelters
RESPONSE: cyclone shelters
RESPONSE: cyclone shelters
Evacuation to ‘safe
havens’ in Cyclone
shelters
’
Winnie-the-Pooh
bear story
IMPACT: Sheer panic!
RESPONSE: Message sent!
RESPONSE: Message received …
RESPONSE: Securing food supplies!
‘A Level’ fieldwork?
‘A Level’ fieldwork – in the rain ...??
RESPONSE:
Heading for home?
….. and living happily ever after?
Somerset: Winter 2014
Floods in catchments
Impacts Responses
Somerset: Winter 2014
Floods:
Physical drivers
Human dimensions
The end!