Table Of ContentRIVER BASIN MODELLING FOR FLOOD RISK MITIGATION
SELECTED PAPERS
Copyright © 2006 Taylor & Francis Group plc, London, UK
BALKEMA - Proceedings and Monographs
in Engineering, Water and Earth Sciences
Copyright © 2006 Taylor & Francis Group plc, London, UK
River Basin Modelling for Flood
Risk Mitigation
Donald W. Knight
The University of Birmingham, UK
Asaad Y. Shamseldin
The University of Auckland, New Zealand
LONDON/ LEIDEN/ NEWYORK/ PHILADELPHIA/ SINGAPORE
Copyright © 2006 Taylor & Francis Group plc, London, UK
Cover photographs:
“The Toyohira River, Japan (courtesy of Ishikari River Development Office)” and,
“The Three Gorges Dam, under construction in 2004, on the Yangtze River, China”
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Table of Contents
Preface vii
1. Introduction to flooding and river basin modelling 1
D.W. Knight
2. The European perspective and research on flooding 21
P.G. Samuels
3. Overview of current perspectives on climate change 59
A. Bronstert
4. The effects of climate change on flooding 77
A. Bronstert
5. The growth and significance of hydroinformatics 93
Roland K. Price
6. The application of hydroinformatics 109
Roland K. Price & Abebe Andualem Jemberie
7. Quantitative precipitation forecasting 127
I.D. Cluckie & D. Han
8. History of radar and radar meteorology 157
G.L. Austin & I.D. Cluckie
9. Topics related to rainfall-runoff models 171
A.Y. Shamseldin
10. Real-time river flow forecasting 181
A.Y. Shamseldin
11. River flow forecasting 197
K.M. O’Connor
12. The Galway real-time river flow forecasting system (GFFS) 215
K.M. O’Connor
13. Introduction to decision support systems 235
M. Bruen
14. Teleflood: forecasting floods in urban areas downstream of steep catchments 249
M. Bruen
15. Present operational flood forecasting systems and possible improvements 267
E. Todini
16. Holistic flood management and decision support systems 285
E. Todini
Copyright © 2006 Taylor & Francis Group plc, London, UK
VI TABLEOFCONTENTS
17. River flood hydraulics: theoretical issues and stage-discharge relationships 301
D.W. Knight
18. River flood hydraulics: validation issues in one-dimensional
flood routing models 335
D.W. Knight
19. Numerical methods for the shallow water equations: 1D approach 387
P. Garcia-Navarro & J. Burguete
20. Numerical methods for the shallow water equations: 2D approach 409
P. Garcia-Navarro & P. Brufau
21. Sediment and debris modelling 429
G.J. Klaassen
22. Case study: flooding conditions at Sondrio on River Mallero 459
G.J. Klaassen
23. Dam break modelling 463
A. Paquier
24. Case studies in dam break modelling 473
A. Paquier
25. Risk and uncertainty in flood management 481
P.G. Samuels
26. The social construction of floods 519
C. Green
27. River basin management: room for the river 537
E. van Beek
28. River basin management: some issues and a case study 555
E. van Beek
29. Barriers inherent in flood forecasting and their treatments 569
R. Khatibi
30. Integration and goal-orientation in flood forecasting and warning 587
R. Khatibi & I.D. Cluckie
Copyright © 2006 Taylor & Francis Group plc, London, UK
Preface
River basin management is now seen to be an increasingly important issue for authorities in many
countries. The variety and extent of the issues involved are considerable, ranging from: flooding
(protection of life, property and infrastructure), provision of water resources (quality as well as
quantity), pollution (water treatment and waste disposal), environmental considerations (river
restoration, wetlands and sustainable floodplain development) and land use (drainage requirements,
soil loss and morphological changes to channels). The European Water Framework Directive is but
one example of the new demands being placed upon environmental authorities responsible for river
and inland waterways.
This book contains edited lectures given by 16 leading European experts at an EU sponsored
Advanced Study Course, held at the University of Birmingham, UK. The course was aimed at dis-
seminating to young researchers and professionals knowledge and understanding from recent
research on river basin modelling, as well as giving them up-to-date views on the management and
mitigation of river flood risk. The primary focus was the nature and flow of information needed to
mitigate the risk of flooding at a river basin level, with a secondary focus of disseminating under-
standing from recent EC research projects related to global and European flooding problems. The
Course lasted two weeks and was attended by 45 participants from 14 countries, selected from 76
applicants. In addition to attending lectures and questioning lecturers, participants also took part
in two field trips and several other related technical sessions.
The book covers many issues, including: a European perspective on flooding, the influence of
climate change, hydro-informatics, hydro-meteorology, rainfall forecasting techniques, rainfall-
runoff models, river flow forecasting systems, flood management and decision support systems,
river flood hydraulics, numerical methods for shallow water equations, sediment and debris model-
ling, dam-break modelling, risk and uncertainty issues in flood management, social and economic
impacts of floods, developments in flood forecasting and warning systems. The coverage is broad,
but integrated, to make it attractive to researchers and professionals working in the field of flood
risk management.
The editors are grateful to the many authors who prepared and delivered their lectures on the
Advanced Study Course, and then edited them subsequently for inclusion in this book. They would
also like to express their thanks to the international scientific panel of experts, drawn from six
Member States, who advised and monitored the selection of material to be presented on the Course.
Particular thanks are due to the European Commission who awarded the University of Birmingham
a grant for the Advanced Study Course, under contract EVG1-CT-2001-65001, and to Mrs Karen
Fabbri who acted as facilitator.
Professor Donald W. Knight & Dr. Asaad Y. Shamseldin
The University of Birmingham
February 2005
Copyright © 2006 Taylor & Francis Group plc, London, UK
1
Introduction to flooding and river basin modelling
D.W. Knight
Professor of Water Engineering, Department of Civil Engineering, The University of Birmingham,
Edgbaston, Birmingham
ABSTRACT: The importance of understanding flood risk management from the perspective of the
catchment, rather than at a purely local level is stressed. The reasons why floods occur due to natu-
ral and man-made causes are highlighted. The differences between fluvial, urban and coastal flood-
ing are summarised, as well as some of the common features between them. Flood disasters are
shown to account for about a third of all natural disasters (by number and economic losses), and to
be responsible for over half the deaths, with the trend worryingly upwards. The principles of flood
alleviation are explained in terms of mainly structural or non-structural measures, and methods for
reducing the overall impact of flooding are described. The philosophy of modelling meteorological,
hydrological & hydrodynamic processes is shown to lead to problems of definition, as well as limi-
tations in the modelling capability at both spatial and temporal scales.
1.1 INTRODUCTION
1.1.1 A catchment perspective
Catchment Management Plans (CMPs) are intended to relate strategic issues governing sustain-
able development and environmental concerns at a river basin or catchment scale. The topography
of each catchment essentially defines the drainage pattern via streams and rivers in such a way that
the volume of potential water falling as precipitation (i.e. rainfall/hail/snow) within the catchment
stays within that catchment and may be accounted for in various ways via, for example in broad
terms, evapotranspiration, surface run-off or groundwater flow. CMPs are thus a means of relating
the flux of water through a catchment to the many practical issues related to that catchment, such
as water resources, drainage capacity, flood mitigation, economic development, land use, planning
controls, floodplain development, transport planning, environmental concerns, pollution control,
nutrient supply, aquatic habitats, river corridor ecology and alluvial morphodynamics. These
issues typically touch on a wide range of political and environmental objectives, and as such
demand multi-objective management.
The concept of multi-purpose river basins in the UK was first enunciated in 1871 by Lord
Montague who argued that ‘The various interests on land and river, navigation and mills, drainage
and water supply, fishing and manufacturers, can be adjusted and developed only by one manage-
ment over the whole river’(Bailey, 1991). This well-founded concept of river basin management
has survived the many changes to river management in the UK over the last 125 years (Knight,
1997), and will assume an even greater significance in the UK and Europe through the imple-
mentation of the EU Water Framework Directive (2000). From the perspective of flood risk man-
agement, it is self evident that individual flood alleviation schemes cannot be considered in
isolation. What happens in one part of the catchment will have some effect on other parts some
distance away. The move to a more strategic, catchment-based approach does not simply mean a
wider view on investment in flood defences. It means taking a holistic view of flood risk manage-
ment, including built development and land management patterns, nature conservation constraints
Copyright © 2006 Taylor & Francis Group plc, London, UK
2 RIVER BASIN MODELLING FOR FLOOD RISK MITIGATION
Map 3 - Distribution of Rainfall
Figure 1.1. Distribution of rainfall in River Tone catchment (NRA, 1995).
and opportunities and emergency planning arrangements. This needs to be based on a long-term
view up to 50 years ahead, backed by sophisticated modelling of the dynamic physical processes
at work in the catchment.
An example of how the distribution of rainfall might vary with ground level within a catchment is
shown in Figures 1.1 & 1.2, taken from the River Tone Catchment Management Plan (NRA, 1995).
The River Tone CMP deals not only with precipitation, but also with the geology & hydro-geology,
water abstraction, pollution, ecology and flood risk issues of the entire catchment. Figure 1.2 shows
the land area above 100 m AOD, the floodplain area and where there are maintained flood
defences. The modelling at a catchment level of the rainfall-runoff process (using a hydrological
model) and the surface runoff (using a hydrodynamic model) are complex tasks. Figure 1.3 shows
a simple schematic representation of a typical catchment, and how the surface run-off from vari-
ous sub-catchments are combined and then modelled in a 1-D system.
Sustainable development and management of floodplains and urban areas requires that a broad
view be taken of river, sewerage and drainage issues. Essentially water can only be ‘stored’ or
‘moved’, and usually there are limitations on both possibilities within particular parts of a catch-
ment. The most sustainable of solutions are likely to be those that address the issue of runoff at
source. The introduction (or re-introduction) of storage into the rainfall-runoff relationship can be
particularly effective when applied near to the point where runoff begins. Storage is also very
effective further down the system, as demonstrated by the Leigh Barrier on the River Medway in
the UK and the Watarase Retention Basin in Japan (23 km2).
The least sustainable of options include further raising of flood defences to constrain a river
‘within bank’, or the construction of new defences to provide protection to new urban areas on the
floodplain. Such solutions generally worsen the problem for other riparian developments, and it
would be easy to say that they should generally only be considered when no other option is appro-
priate or viable. However, this is too simplistic an approach, and the quest should be to find a solu-
tion that suits the circumstances in each particular case. For example, the extremely successful
Gainsborough Flood Alleviation Scheme in the UK, which combined the need for flood risk
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INTRODUCTIONTOFLOODINGANDRIVERBASINMODELLING 3
Map 11 - Floodplain
Figure 1.2. High ground and floodplain areas in the River Tone catchment (NRA, 1995).
Figure 1.3. Schematic representation of modelling runoff in a typical catchment (after Shaw, 1994).
Copyright © 2006 Taylor & Francis Group plc, London, UK
