Assessing Urban Water Strategies for Total Water Cycle Management

Magnus MogliaSenior Research Scientist, CSIRO Land and Water

Collaborators: Shiroma Maheepala, Daniel Kinsmann

5 December 2012

Urban Water Security Research Alliance

Total Water Cycle Management Plan

• The objective is to identify a strategy that has the potential to  move towards a more sustainable state than the current state

•

Assessing against multiple criteria•

Methods to quantify criteria for alternative water strategies (or scenarios)

‐100%‐75%‐50%‐25%0%25%50%75%100%

Scenario 1 Scenario 2 Scenario 3

OzoneDeplet'n

Fossil FuelDeplet'n

MineralsDeplet'n

MarineEcotox

FreshwaterEcotox

TerrestrialEcotox

HumanToxicity

potablesavings

TNreduct'n

GHG

Broad environmental  issues – highlights potential future concerns

TWCM: decision problem

• Several cars to choose from•

Indicators help us make an informed decision

•

Litres/100kms•

Safety grading

•

On road performance•

Comfort

•

Price •

Etc 

• Uncertainty is an important factor•

Lemons

•

Brand consistency• Value and prioritisation is subjective• Planners make decisions on behalf of other people, with other 

peoples money, and have reasons to be risk‐averse

Decision Supporting Framework

Subjective Logic Subjective Logic 

Informed actionInformed action

eWater CRC Framework reported in Blackmore et al., 2009.

Handling uncertainty?

A.

All values are absolute; in reality they are uncertain (according  to some probability distribution?)

B.

Estimates, including of uncertainty, are difficult to make on the  basis of incomplete information.

C.

(Personal or Model based) Judgments are an integral part of  assessments

1.

How do we incorporate uncertainty

in estimates into  assessments?

2.

How do we incorporate trust

in judgments into assessments? 

Subjective Logic: basis

b = beliefd = disbeliefi = ignorance

DisbeliefBeliefBelief

IgnoranceIgnorance

OUTCOME SPACE Example:

Will Australia beat South Africa in the cricket?

Some months ago:Belief = 0.1Disbelief = 0.1Ignorance = 0.8

Now:Belief = 0.1Disbelief = 0.8Ignorance = 0.1

P(X) = 0.5

P(X) = 0.85

Case Study: Subjective Logic applied to TWCM

Assessment approach Variable

Source simulations TNTPTSSFlows

Lifecycle cost Project cost

Caboolture River catchment with CIGA – sub‐catchment 63Caboolture River catchment with CIGA – sub‐catchment 63

A)

Low intensity  B)

Medium intensity 

C)

High intensity

A)

Low intensity  B)

Medium intensity 

C)

High intensity

An illustration of how the process / method is applied.

Scenarios

Scenario  Management solutions1 Future development meet 80/60/45 % load reduction for TSS/TP/TN

1 Future development meet QDC alternative water supply

1&2 Increased implementation/enforcement of E&SC management practice

1&2 Waterway and riparian revegetation of 3rd and 4th order streams 

1&2 Education and/or capacity building and investment in incentive schemes

1&2 Prevention of illegal stormwater inflow  connection to sewer

1&2&3 Future greenfield development WSUD measures to achieve no‐worsening

1&2&3 Recycled water supplied to urban users

1&2&3 Stormwater harvesting

Basic model structure

Climate

Scenario

Source EMS data generation

Source EMS data generation

• Model above applied for each land use separately (urban, green space  etc)

• Once for each mitigation scenario (1, 2, 3)• 30 year simulation period run outputting daily data• Constituent monthly means and deviations for El Niño, La Niña and 

normal Southern Oscillation periods calculated in post processing

Time consuming!Time consuming!

Source simulations results

InputsFlow TN TP TSS

MeanStandard 

deviation Mean

Standard 

deviation Mean

Standard 

deviation Mean

Standard 

deviation

Scenario 1 La Nina 15.89 1.07 9.21 1.14 7.13 1.24 13.09 1.38Scenario 1 El Nino 12.96 1.10 6.29 1.15 4.21 1.25 10.16 1.38Scenario 1 Normal 15.64 1.11 8.97 1.17 6.89 1.28 12.84 1.41Scenario 2 La Nina 13.41 1.07 6.73 1.14 4.65 1.24 10.34 1.34Scenario 2 El Nino 12.96 1.10 6.29 1.15 4.21 1.25 9.90 1.36Scenario 2 Normal 12.96 1.10 6.29 1.15 4.21 1.25 9.90 1.36Scenario 3 La Nina 13.41 1.07 6.68 1.13 4.56 1.23 10.18 1.33Scenario 3 El Nino 12.96 1.10 6.24 1.14 4.12 1.24 9.74 1.36Scenario 3 Normal 13.15 1.11 6.44 1.16 4.32 1.27 9.95 1.38

Convert to 

appropriate 

distribution & 

discretise

Inputs Flow50% worse Same 25% better 50% better 75% better 90% better

Scenario 1 La Nina 44.0% 25.0% 12.0% 13.0% 4.0% 2.0%Scenario 1 El Nino 0.2% 1.2% 2.0% 8.4% 13.8% 74.3%Scenario 1 Normal 35.7% 24.6% 13.2% 16.0% 6.7% 3.8%Scenario 2 La Nina 1.0% 2.8% 4.1% 13.9% 18.7% 59.8%Scenario 2 El Nino 0.2% 1.2% 2.0% 8.4% 13.8% 74.3%Scenario 2 Normal 0.2% 1.2% 2.0% 8.4% 13.8% 74.3%Scenario 3 La Nina 0.7% 2.8% 4.1% 13.9% 18.7% 59.8%Scenario 3 El Nino 0.2% 1.2% 2.0% 8.4% 13.8% 74.3%Scenario 3 Normal 0.5% 1.9% 2.9% 10.8% 15.9% 68.0%

NPV-min NPV-max

Scenario 1$

50,080 $ 10,516,727

Scenario 2$

65,105 $ 11,268,924

Scenario 3$

2,238,561 $ 15,254,263 Mean Std

Scenario 1$

5,283,404 $ 2,670,063

Scenario 2$

5,667,014 $ 2,858,117

Scenario 3$

8,746,412 $ 3,320,332

Cost estimation

Scenario management solutionsNPV total cost (2011 $) min NPV cost max NPV cost

1 Future development meet 80/60/45 % load reduction for TSS/TP/TN $ 7,700,448 $ 5,008 $ 7,712,267

1 Future development meet QDC alternative water supply $ 1,419,358 $ 45,072 $ 2,804,461

2 Increased implementation/enforcement of E&SC management practice $ 636 $ 1 $ 1,002

2 Waterway and riparian revegetation of 3rd and 4th order streams $ 180,287 $ 15,024 $ 751,195

2 Education and/or capacity building and investment in incentive schemes not costed not costed not costed

2 Prevention of illegal stormwater inflow connection to sewer not costed not costed not costed

3 Future greenfield development WSUD measures to achieve no-worsening $ 7,700,448 $ 10,016 $ 7,712,267

3 Recycled water supplied to urban users $ 1,852,947 $ 976,553 $ 4,086,500 3 Stormwater harvesting $ 3,450,488 $ 1,251,991 $ 3,455,496

Shiroma MShiroma M

Added values and climate

Outcome variable Cost per tonne ($/t)TN $273,000/tTP $220,000 /tTSS $213 /tFlow $0.2 

Pollutant costs for “no worsening”

LTA of ENSO conditions

Murray HallMurray Hall

SOI Time SeriesSOI Time Series

Strategy satisfaction

Cost range

Added value*

No added value  Some added value Significant value 

0 to $1,000,000 $1,000,000 to $3,000,000$3,000,000 to 

$15,000,000

<$1,000,000 1 0.3 0.1

$2,500,000 3.5 1.2 0.2

$5,000,000 3.5 1.2 0.2

$7,500,000 12.5 4.2 0.7

$10,000,000 17.5 5.8 1.0

>$10,000,000 30 10.0 1.7

Extremely unlikely (1%)Quite unlikely (10%Neither unlikely or likely (50%)Quite likely (75%)Highly likely (90%)Extremely likely (99%)

Years before value >= cost

Note: Should  be done by 

stakeholders

Note: Should  be done by 

stakeholders

Reliability of information –

illustration only

• Inherently subjective• We use “cues” to help assess

reliability – i.e. what categorises rigorous analysis? Existence of sensitivity analysis, high level of scrutiny of data sources, critical peer review, etc.

Input data Assigned reliabilitySource EMS Neither reliable or 

unreliable (50%)Lifecycle 

CostingSomewhat reliable 

(75%)

Lack of justification for  parameter values, consistent 

use of linear functions, errors  in running models, black‐box

Lack of justification for  parameter values, consistent 

use of linear functions, errors  in running models, black‐box

Something we have some  experience with. Assumptions 

clear. Parameters not plucked  completely out of thin air.

Something we have some  experience with. Assumptions 

clear. Parameters not plucked  completely out of thin air.

Software: Intelfuze

• Intelfuze: software was in Beta‐testing (Subjective Logic is a novel  and patented analysis approach within a software) – for Bayesian  Networks

http://www.veriluma.com/products/metafuze/

Results

Scenario Prob(strategy satisfaction)

“Trust” of assessments

1 56% 33%*2 75% 49%3 61% 22%

During El Nino conditions, Scenario 1 is the preferred option! => you can explore sensitivity to climate and other factors

Model is sensitive to formulation, i.e. cost-benefit acceptance matrix and discretisation process.

*This is indicated in the software with a warning: derived observation has the potential for being derived from inadequate information.

Concluding words• Assessment result aligns with MCA recommendations, but 

Subjective Logic method provides additional information on  uncertainty and reliability

•

Underlying reliability of assessments – needs consideration of the reliability  and justification of input parameters

•

Can explore sensitivity to underlying factors such as climate• Model is sensitive to •

Cost‐benefit acceptance matrix => requires stakeholder input

•

The discretisation

process => this is a concern and requires careful thinking• Model can relatively easily expanded to explore sensitivity to 

other factors• Source EMS model is not set up to easily undertake sensitivity 

assessments for catchment modelling•

First, clarify reliability and justification of input parameters

Urban Water Security Research Alliance

THANK YOU!

www.urbanwateralliance.org.au