1
Floods - Past and Present IssuesAddress
given to The Royal Scottish Society of Arts11th
February 2002EdinburghbyProfessor George
Fleming FREng FRSE FICE FASCE

• Professor of Civil Engineering, University of
  StrathclydeManaging Director of
  EnviroCentreChairman, ICE Presidential
  Commission Undertaking a Technical Review of
  Flooding in
• England and Wales

2

• How can communities be better prepared for
  floods?
• Why is it not yet a requirement of the Building
  regulations that the lowest floor of a building
  on a flood plain is above the 1 in 100 year flood
  level?
• Should all buildings on flood plains be
  constructed of flood resistant materials?
• Why is there no national strategy for such
  mitigation systems?
• Could a national flood insurance programme be
  linked with these requirements?

3
-V-
4
INTRODUCTION
5

• England and Wales - 2000
• River Tay - 1993
• River Ness - 1989
• The Clyde - 1977
• Bristol - 1968
• Lynmouth - 1952
• Medway - 1814

6
Risk

Expenditure Cycle
Risk

Expenditure Cycle
7

• Depute Prime Minister
• John Prescott MP described the severe weather and
  flooding that dramatically disrupted parts of the
  country in Autumn 2000 as a wake-up call to the
  impacts of climate change.

8
THE HISTORICAL CONTEXT
9
A flood is a great flow of water, causing
overflow and inundation (Chambers, 2000(2)).
The factors causing a flood to occur are extremes
in meteorology and hydrology, coupled with
changes to river hydraulics caused by land use
and alterations to river geomorphology
10
The Forth Clyde and Union Canal
11
Development in Flood Plains
12
HISTORICAL FLOOD ESTIMATION
13
Historical Data Collection
14
Risk of a one in 100 year flood event

• Only possible once in 100 years
• One in 100 chance of flooding

X
?
15
Regional Flood Frequency Curve Scotland (
Biswas
Fleming, 1966)
Regional Flood Frequency Curve Great Britain
(NERC, 1975)
Regional Flood Frequency Curves
16
x
x
5.0
x
Analysis of Flood Frequency Curves
4.0
x
x
x
3.0
x
2.0
1.0
T
2
5
10
25
500
100
1000
y1
1
2
3
4
5
6
7
8
0
-1
Regional Flood Frequency Curve Scotland (Biswas
Fleming, 1966)
Regional Flood Frequency Curve GB (NERC, 1975)
x
17
Flood Estimation Techniques
18
THE CURRENT PROBLEM
19
flood protection
flood protection
background conditions
background conditions

type of defence

flood history



d

design standard

number of properties at risk

c

condition of defence
environmental
environmental
flood prediction
flood prediction
flood risk
flood risk

climate change


source of flooding


environmentally sensitive areas


reliability of forecasting



long and short term impacts

warning time

social
social

flood awareness

flood type
flood type

resilience of population


nature of housing


depth of flooding

economic
economic

social disruption



flood velocity

infrastructure at risk

rate of flood rise


commercial disruption

wave action


services disruption



potential agricultural losses
Factors Affecting Flood Risk
20
Effect of Constraining Flood Plains
21
Effect of Constraining the Flood Plain
22
Leigh Barrier in Operation
23
Flood Defences at Gainsborough
24
FUTURE FLOODING ISSUES
25
(No Transcript)
26
Projected Effects of Climate Change on Run-Off
for Clyde Catchment
27
(No Transcript)
28
Presidential Commission to Review Flooding in
England and WalesInstitution of Civil Engineers
One Great George StWestminsterLondon, SW1P
3AATel 0207 665 2232www.icenet.org.uk/preside
ntial.html
29
CONCLUSIONS
30

• How can communities be better prepared for
  floods? A For flood risk to be more clearly
  explained to both professional and lay person.
• Why is it not yet a requirement of the Building
  regulations that the lowest floor of a building
  on a flood plain is above the 1 in 100 year flood
  level? A Building on the flood plain needs to
  be carefully assessed. There is more to do than
  a simple building regulation.
• Should all buildings on flood plains be
  constructed of flood resistant materials? A
  Existing buildings need flood proofing. New
  buildings on flood plains need to have flood
  resistance designed in as well as flood impact
  designed out.
• Why is there no national strategy for such
  mitigation systems? A There is an emerging
  strategy in England and Wales to manage flood
  risk. A similar strategy has to be developed in
  Scotland which takes us beyond just flood
  warning.
• Could a national flood insurance programme be
  linked with these requirements? A Flood
  insurance programme must be consumer-driven and
  be flexible. A national flood insurance
  programme would be as complicated as it was
  ineffective.

31
Warning systems will be important, but a flood
management system must be introduced in order
that community and profession can work together
and learn to live with our rivers.