UrbanBEATS Seminar Series 2012 - 01

Seminar Series, 2012
www.urbanbeatsmodel.com

Integrated Modelling Revisited
The Urban Drainage System and Beyond
Peter M. Bach
Centre for Water Sensitive Cities
Department of Civil Engineering
Monash University, VIC 3800, Australia

18th May, 2012
Co-authors: Wolfgang Rauch, Peter S. Mikkelsen,
David T. McCarthy, Ana Deletic

Seminar Series, 2012

01 – Integrated Modelling Revisited : The Urban Drainage System & Beyond
(May 18th, 2012 – Today)

02 – UrbanBEATS : Overview of a Virtual Urban Water System Tool
(June 15th, 2012)

03 – Digital Cities : Development of Spatial Algorithms for Urban Water Models
(TBA)

04 – Optioneering WSUD : Modelling decentralised water management planning
(TBA)

05 – TBA

“...Model /ˈ ɒd(ə)l/
m

(2) a thing used as an example to follow or imitate

(3) a simplified description, especially a mathematical one, of a system or
process, to assist calculations and predictions

(4) a person employed to display clothes by wearing them
...”
(Source: Oxford Dictionary)

Seminar Series, 2012 | #01 Integrated Modelling Revisited | Peter M. Bach | www.urbanbeatsmodel.com | 1/32

...from the literature...

“... An engineering model is not the reality, but a limited,
simplified and partial representation of reality, i.e. a tool
built for practical applications....”
– J. L. BETRAND-KRAJEWSKI, 2007 WATER SCIENCE & TECHNOLOGY

“... A „number-crunching‟ or „sledge hammer‟ approach
to theory-building....”
– M. BATTY, 2010 , CAMBRIDGE UNI PRESS

“...A model is any representation of a real system that can
be used to simulate certain features of the more complex
real system...”
– H. JONES, 1992 CAMBRIDGE UNI PRESS


Modelling – A “Not-So-Complex” Illustration

Users
!!

MODEL
SETUP & INPUTS OUTPUTS
Problem Definition a “black box” Predictions
Aims & Objectives Analysis
Case Study & Scenarios Interpretation
Parameters& Data
Calibration/Optimization/Training

REFINEMENT, ITERATION, RE-EVALUATION


Why use models?

Science Design
Cool &Geeky!
Quantitative
Epistemological devices

Virtual Laboratory
Cost-effective
Rigorous

Confidence
Ideas Testing
EXPLORE
Assess Uncertainty
“Wicked Problems”
Economics Curiosity

“...Integration /ɪntɪˈgreʃ(ə)n/
ɪ
the linking and coordination of various parts or aspects

...”
(Source: Oxford Dictionary, with a little difficulty...)


Examples of „Integration‟


Today‟s Seminar

 Once upon a time...

 Integrated Modelling and the Ambiguities therein

 Organising integrated models of urban water systems...

 Developing Integrated Models, what complexity has been
added?

 Current Adoption in Practice, where do we stand?

 Future Outlook, is there hope?


Our journey begins around the late 1970s


Our journey begins around the late 1970s

Receiving Water Body

Sewer Network

Wastewater Treatment Plant
Source: Gujer et al., 1982

adapted from Bach et al. (submitted)
and since then...

I.M. Guidelines
for Urban Drainage
Water Quality Systems
Increased Focus
Awareness

?
Real-time Control
Fieldwork New Types of
First concepts Integration Inter-disciplinary
Model
Integration
Advancements New Modelling
Technologies Legislation Changes
Softwares Emerge

1970s 1980s 1990s 2000s Time

First Emerging 1993 2000 2002 ~ 2006 2012
mentions interest in 1st INTERURBA EU Water 2nd IUWM Present
of integration understanding Conference Framework INTERURBA paradigm Day
component Directive Conference emerges
interactions

So what is “Integrated Modelling”?

“...modelling of interactions between two or more urban
water system components...”
– Rauch et al., 2002, Olsson and Jeppsson, 2006

“...ability to focus on understanding the behaviour of parts of
the system with respect to the broader picture...”
– Beck, 1976

“... recognises both the positive and negative feedbacks
between components and exploits these for significantly more
efficient solutions...”
– Marsalek et al., 1993, Mitchell et al., 2007


• Positive Feedback
• Negative Feedback
• Short & Long-term Effects
• More than the Sum of Parts

Subsystem
Subsystem

Subsystem
Subsystem

Subsystem
Subsystem

Subsystem


Users
!!

“...the prerequisite to an SETUP & INPUTS
MODEL
OUTPUTS
a “black box”
integrated approach is the Problem Definition
Aims & Objectives
Case Study & Scenarios
Predictions
Analysis
Interpretation

identification of the ‘‘axes and Parameters& Data
Calibration/Optimization/Training

planes’’ in which integration
REFINEMENT, ITERATION, RE-EVALUATION
needs to take place...”
– Rauch et al., 2005
Sub-Systems
Disciplines

Processes


Yet...

 The body of literature is massive, repetitive and
ambiguous based on two kinds of templates

 We are faced with “linguistic uncertainty”

 Integrated is “...ill-chosen and ambiguous term as it implies a
sense of completeness...” – Rauch et al., 2005

 We lack a means to classify models based on:

 different scopes of the urban water system
 considerations for model development


Organising Integrated Modelling in UWS
Integrated urban water system models IUWSMs
Integrated urban water infrastructure models IUWIMs

Integrated urban drainage models Integrated water supply models
Integrated component-based models
IUDMs IWSMs
 Catchment Drainage,
ICBMs
Runoff and Pollution  Water demand patterns
Water WWTP Natural
 Sewer Transport Supply Treatment  Reservoir Storage-behaviour
 Combined Sewer Overflow System System  Decentralised water sources
 Receiving Water Body Natural  Water distribution network
Sewer
Quality Water Body  Water treatment plant
Processes
 Flood Protection

Decentralised & Total Urban Water Cycle Water Resources
Water recycling
Centralised systems (Supply & Drainage) Allocation

Soil & Air Social
Local/Regional Economic Ecological
Quality Behaviour Energy Models
Climate Model Models Models
Models Models

Environmental Decision Support Systems EDSS


Some Examples

 ICBMs:
• Benchmark Simulation Model No. 2 (Grau et al., 2007)
(whole of wastewater treatment plant model)

IUDMs & IWSMs:
• SIMBA (IFAK, 2007)
(sewer system and wastewater treatment plant)
• SAMBA, RUMBA, FOXTROT (Harremoes & Rauch, 1996)
(sewer system, wastewater treatment plant, receiving
waters)
• EPANET (Rossman, 2000)
(simulation of water distribution networks
& storages)


Some Examples

 IUWIMs:
• MUSIC (eWater)
• UrbanDeveloper (eWater)
• Aquacycle (Mitchell et al., 2001)
• MIKE URBAN (DHI)

 IUWSMs: current only sparse
• Work by Fagan et al., 2010
• VIBe (Sitzenfrei et al., 2010)
• OpenMI (OpenMI Association, 2010)
• DAnCE4Water & UrbanBEATS


Developing Integrated Models
Define Aims & Objectives and Source: Bach et al. (submitted)
Make initial selection of Model
Aims & Objectives Features (from Table 3)

Identify/Quantify/Acknowledge/Track reducible and irreducible UNCERTAINTY
Select relevant state variables
List relevant Interactions
& delineate system boundary
between system components
(level of integration e.g. IUDM)
Find/Make the
models
Select existing relevant models
for each component Determine Transfer Functions
(develop if non-existent) (conversion processes, feedbacks)

String’em together
Select method of integration &
Iterative

construct integrated model
Refine if necessary

Determine calibration method Define “verification criteria” of
Calibrate & Run & data requirements the integrated model

Analyse Model Outputs
Calibrate & Run the Model (according to performance and
verification criteria)
Interpret Output
Cross-check Results with
Aims & Objectives


Key Considerations
Model Structure Empirical vs. Conceptual vs. Mechanistic
Primary vs. Surrogates
Deterministic vs. Stochastic
Simulation Config. Sequential vs. Parallel
Online vs. Offline
Spatial Detailing Branched vs. Looped
Distributed vs. Lumped
Temporal Detailing Continuous vs. Discontinuous Simulation
Uniform vs. Variable Time Step
Process Nature Water Quantity (Hydrologic & Hydraulic)
Water Quality (Physical, Biological, Chemical)
Computation Single Core vs. Multi-Core Processing
Single run vs. Optimisation vs. Benchmarking
Software Supermodel vs. Interface vs. Hybrid


Key Considerations – Sequential vs. Parallel
Sequential: “One-node-at-a-time”
for entire time period
Parallel: All at once
“One-time-step-at-a-time”
1 4
Catchment 1 Treatment 1

2 5 6
Catchment 2 Treatment 2 Storage 1

3 t1 7
t2
Catchment 3 River


Key Considerations – Single vs. Multi-core Processing

Source: Burger et al., 2010 WST


Key Considerations – Supermodel, Interface & Hybrid

Sewer Sewer
Sewer
+ +

Wastewater Wastewater
Treatment Wastewater Treatment
Plant Treatment Plant Plant

+

Receiving
Receiving Water Receiving
Water Body
Body Water Body

Supermodel Interface Hybrid


The Pragmatism vs. Parsimony Debate


Calibrating and Validating these Beasts

 Three methods identified:

#1 :: calibrate the whole integrated model at once

#2 :: start upstream, then gradually move
downstream, quantity before quality

#3 :: calibrate individual models first, then integrate
them


Calibrating and Validating these Beasts
 Integrated models as “unwieldy” and “highly complex” – a
technical and logistical challenge!

 Error propagation, equifinality and sometimes unavoidable
auto-correlation more pronounced with increasing
complexity

 Calibration/Validation feasibility decreasing with larger
integrated models – still useful?

 Overcome data limitations with semi-hypothetical case
studies and exploration

 Overcome overparametrisation by using simpler surrogate
models

Uncertainty

 Types:
• Statistical (outcomes known and quantifiable)
• Scenario (outcomes known but not quantifiable)
• Qualitative (not all outcomes known nor quantifiable)
• Recognised Ignorance

 Statistical received great attention (many methods to
quantify)

 Scenario partly explored

 Should integrated modelling field rely on classical
uncertainty estimation methods?


Driving the Adoption of Integrated Models

(1) Global Change & the IUWM Paradigm

(2) Changing Legislation

(3) Diversity of Integrated Model Use


Driving the Adoption of Integrated Models

 Diversity e.g. Semi-Hypothetical/Virtual Case Studies
(Sitzenfrei et al. 2010, Urich et al. 2010)


Barriers that we still face Data Requirements

User-friendliness
Legislation

Uncertainty
Communication

Model Complexity


So what does the future hold?
 The literature‟s Key goals
 More „now-casting‟

 More transparent process in using
integrated models

 More interdisciplinary work

 The direction of future research(?) - “Virtual Playgrounds”
encompassing the technical and non-technical

 Fragmentation in practice needs to be overcome

 Legislation needs to evolve more than it has

 Participatory approach

Concluding Remarks

 Limited Success Story for Integrated Models of Urban
Water Systems

 Good grasp of the field in theory, need to move towards
unravelling more complexity

 Slow uptake in practice, but there is progress

 This collation of knowledge is also the starting point for
new innovations in modelling

Contact me for more information and the in-depth review


Thank you!


UrbanBEATS Seminar Series 2012 - 01

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