Overview of flood risk modelling activities

1. Introduction to Computer-based Flood
Risk Modelling in the UK and Overseas –
Coventry University
• Visiting Lecturer on
• Catchment Hydrology, Hydraulics and River Flood Modelling
• Coventry University
Dr Rahman Khatibi
GTEV-ReX
29 November 2016
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2. • Outputs of construction Industry:
– In 2014 the turnover was £115 Bn
– In 2013, the UK GDP of £1.6 Tn
– So the turnover was 7% of the GDP
• Development Projects:
– Facilitated by a planning system
– Run by Local Planning Authorities (LPA) of Local Authorities
– “Decision-making by participation”
– The system is plan-led through National Planning Policy
Framework (NPPF)
• Scope of Planning by LPA in the year ending June 2014:
– granted 350,200 permissions
– 88% of decisions ended up by granting permission
1. Setting the scene (1)

3. Environment
Prudent use of natural
resources and effective
protection of the environment
Society
Social progress which
recognises the needs of
everyone
Economy
Maintenance of high and
stable levels of economic
growth and employment
1. Setting the scene (2)
SustainabilityMarket-pulled Hydraulic Systems Science-pushed Educational Topics

4. • Water supply systems
• Water treatment works
• Reticulations systems
• Rising mains
• Gravity mains
• Irrigation drainage
• Irrigation supply systems
Market-pulled: water
systems:
• Flood Risk Management systems
• Erosion/sediment problems
• Water quality problems
• Drainage systems
• Sewerage systems
• Sewage treatment works
• SuDS
• Other drainage systems
Modelling Bridges the
gap
• Pipes: rigid, elastic
• Control valves
• Intakes/reservoirs
• Surge suppression units
• 2D Floodplains
• HD Rivers/
• Diffusion Analogy
• Kinematic waves
• Discharge routing
• Reservoirs
• A host of control units
• Inflows/outflows
• Hydrological cycle
• Hydrology
• Modelling software
1. Setting the Scene (3)
Science-pushed:
Hydraulics /hydrology
•Basic concepts
•Conservation of momentum
•Conservation of mass
•Forces, hydrostatics
•Pipe flows
•Pipe control units
•Boundary layers
•Fluid machines
•Open channel flows
•Control in O.C.
•Sediment transport
•Groundwater flows
•Flood estimation
•River Engineering
•Coastal engineering
•Modelling
•Modelling software

5. Computer-based Flood Risk Modelling -
summary
Setting the scene
1. Outline history of modelling
2. Purpose/needs
3. Types of modelling
• A full overview
• Model building
• Information contents
4. Steady/unsteady conditions
5. Functions and usage of models
6. Business drivers for modelling

6. 2. Outline history of modelling
•Advent of Computers
•Rise of software engineering
•Increasing data
•Modelling practice
Fundamental thinking of 18th-19th Century
Intellectual Capital of hydraulic Traditional component hydraulics
Tapping on the intellectual capital
By a fury of simplified methods •Empirical hydraulics
•Design and operations
•Hydrology
•Component analysis
18th-19th
Century
1900
1950
1960
1980
1990
2000
Beck: risk increasing
Intelligent
clients
Modelling
Modelling and
modelling
Emergence of flood risk management

7. • Models are tools for decision-making
• Without models: solutions at risk of being arbitrary, ad hoc
• With models: solutions can be defensible
Without models: the onus is on you
With the models: the onus is on the models and on
modelling practices
• Model defensibility: models must be defensible by:
– Employing best practice
– Having systematic checks by independent modellers
– Putting in place QA procedures and TQM
2. Purpose/needs

8. 3. Overview of types of modelling(1)
Considering Flooding Risk from all sources
•0D
•1D
•1D+
•2D-
•2D
•2D+
•3D
Surfacewater
models
Fluvial models
(channels + floodplains
Coastal models
(tides + surges)
Meteorological models
Global, regional, local
Groundwater
models
Sewers
models
Reservoir failures
models
Hydrologic
models
Erosion
Data
Remote sensingSpace scale
Time scale
Survey data
Survey data
LiDAR
Gauges
Modelling systems
ModularityInterfaces
Time scale
Space scale
Trigger events
Overtopping Breaching
Blockage
Inundation
Land use
RuralUrban
Greenfield
Semi-urban
Brownfield
New development
Flow regimes
SubcriticalSupercritical
Kinematic Role waves
Data-driven models
•Regression,
•Machine-learning
•AI (ANN, GA, GEP, FL) Distributed Models
•Design modelling
•Real-time forecasting
•Flood modelling
•Low-flow modelling
•Operations modelling

9. 04/12/2016 University of Glamorgan: - Rahman Khatibi
1D Reservoir
Medium
Resolution
2D Domain 2
2D Domain 3
Low
Resolution
Contours
Extended 1D
Sections
Contours
High
Resolution
2D Domain 1
Embedded
1D Model
Flood
Relieve
Channels
Road
Schematise and divide the system into domains
3. Types of modelling – model Building (2)
Hydraulic Units
• Basic concepts
• Forces – conservation of
momentum
• Storage – conservation
of mass
• Pipes: rigid, elastic
• Control valves
• Intakes/reservoirs
• Surge suppression units
• 2D Floodplains
• HD Rivers/
• Diffusion Analogy
• Kinematic waves
• Discharge routing
• Reservoirs
• A host of control units
• Inflows/outflows
• Hydrological cycle
• Hydrology
• Modelling

10. 3. Types of modelling – model Building (2)

11. • No equations
• Continuity+ 1-momentum
• Mass balance
• Mass balance + Diffusive FP
• Continuity+ 2-momentum
• Continuity+ 2-momentum + a
good solver
• Continuity+ 3-momentum
• Longitudinal variations
• Classic 2-stage channels
• Attenuating floodplains
• Hydraulic jumps/Roll waves
• Mixing required
• Storage floodplains
• To model lateral variations
• Urban, coastal, floodplains
• Slow overland flows
• Fast spreading • 0D
• 1D
• 1D+
• 2D-
• 2D
• 2D+
• 3D
3. Types of modelling – 1D/2D/3D & integrated modelling (3)
• There are many brands of models now
• For open channels these include: FEH, HEC-RAS, Flood Modeller Pro,
TUFLOW, JFlow, MIKE-21, InfoWorks
• We use one brand but this should change as we should extract
consensus from models

12. Order 1 Order 2 Order 3KEY
Rules of thumb
Heuristic rules
Blackbox modelling
Conceptual modelling
Hydrological Routing
Kinematic routing
Hydrodynamic routing
Models with updating
Empirical approaches
Uncertainty
Reliability
Models used for Rivers
Resolution,reliability,informationcontent
Overall Attributes
Individual Attributes
Uncertainty,Susceptibilitytoproblems
3. Types of modelling –information/uncertainty (4)

13. • Steady state: No variations in time dimension
– a special case of unsteady flows
– Some problems can be approximated to steady flows
– gives fast and conservative solutions
• Unsteady state: Variations in time dimension
– Most of the problems are unsteady
– Modelling unsteady flows is an involved activity
– Simulating unsteady flows give a deeper insight into the
complex flow processes
• Real-time modelling
4. Steady/unsteady conditions

14. • Each solution by modelling is an anecdote and good to
gain an insight into processes
• Models do more: tools of risk-based decision-making:
• So, what is risk? (hazard * its probability)
5. Functions and usage of models

15. Model uses:
• Study system operations
• Carry out design works
• System performance under extreme conditions
• Performance under proposed developments
• Assess impacts of changes (EIA and ES)
• Study conditions under predefined events
• Detect acts, which have triggered adverse
conditions
5. Functions and usage of models

16. • The European Flood Directive
• The European Water Directive
• The EIA Directive (85/337/EEC)
• Flood and Water Act 2010
• Replacements should come in due
course
• National Planning Policy Framework(NPPF) –
England
• Technical Advice Note 15 (TAN15) – Wales
• Scottish Planning Policy (SPP) 7
6. Modelling Business Drivers: Legal Drivers (1)

17. • Flood Risk
Management Plans
• River Basin
Management Plans
• Catchment Flood Management Plans (CFMP)- EA
• Shoreline Management Plans (SMP) – LA
• Surface Water Management Plans (SWMP) – EA?
• Regional Flood Risk assessment (RFRA) – LA
• Strategic Flood Risk Assessment (SFRA) - LA
6. Modelling Business Drivers: Competent Authorities (2)

18. • Flood Maps (Zone 1, Zone 2, Zone 3)
• Flood hazard maps:
– the flood extent;
– water depths or water level, as appropriate;
– flow velocity
Approx. Location of the Site
6. An example of information issued by competent authorities (3)

19. • A masterplan:
– the process, to undertake analysis & prepare strategies
– the proposals, to plan for major change
– Includes buildings, spaces, movement strategy, land use
– focussed on sustainable principles
• A masterplan is a sophisticated model and shows,
among many things, ways of integrating
communities into the built/natural environments
6. Modelling Business Drivers: Masterplanning (4)

20. 6. Examples of Masterplanning (5)

21. 6. Setting the scene: Quantitative Modelling (6)

22. 6. Examples of Masterplanning – Urban Flooding (7)

23. 6. Examples of Masterplanning: SuDS (8)

24. Conclusion
• Open eyes from the past to the future
• A critical mind as everything changing
• Academic education and industrial training go hand-in-hand
• Prior to 2000: deterministic modelling, implying certainty and
the delivery of truth
• Since 2000: models regarded as information tools
–uncertainty estimation becoming integral to modelling
–Models serve as tools of risk-based decision-making
• There are many brands of models now (FEH, HEC-RAS, Flood
Modeller Pro, TUFLOW, JFlow, MIKE-21, InfoWorks)
• We use one brand but this should change and we should extract
consensus from models

25. Thank you and
See you later for questions