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Local Government & Shires Association Water Management Conference, Wagga Wagga, 22-24 July 2012
Water Quality Risk Management:
Accounting for a Variable Climate
Dr Ryan Signor
Water & Environment – Risk Management Consultant GHD Water
A variable and uncertain climate will pose
challenges to water authorities.
Regardless, a safe and reliable water supply
will always be a major priority for
communities, and those who serve them.
• Future climate and weather patterns represent a
major uncertainty that requires monitoring,
management and planning
• Scenarios have been modelled based on storylines
about global responses to climate change
• Models are complex and there can be significant
variability among the scenario outputs; for example,
projections for Dubbo (NSW):
What to do about the weather? A1FI
B2
A2
B1
A1T
A1B
Greenhouse Gas Emission Scenarios to inform climate change
projections, from Intergovernmental Panel on Climate Change
(IPCC), 2007, Climate Change 2007: Synthesis Report.
Contribution of Working Groups I, II and III to the Fourth
Assessment Report of the Intergovernmental Panel on Climate
Change [Core Writing Team, Pachauri, R.K and Reisinger, A.
(eds.)]. IPCC, Geneva, Switzerland.
Climate change projections under
different year and emission scenarios
for Dubbo, NSW. From Appendix B of
Commonwealth Scientific and
Industrial Research Organisation and
Australian Bureau of Meteorology
(CSIRO & BoM), 2007, Climate
change in Australia: Technical Report
2007, Australian Government,
Canberra, Australia.
Risk is “the impact of uncertainty on objectives” (ISO 31000:2009)
Adaptive management involves a process of identifying objectives and continually
assessing, better understanding, monitoring and responding to the risks that a
changing climate may present to meeting them
Risk management lends itself to climate adaptation
Adaptive management for the water industry*
* The depicted planning cycle is Figure 1 from: Short et
al; 2012, ‘Managing Adaptation of Urban Water Systems
in a Changing Climate’, Water Resources Management,
26(7):1953-1981
“Ensuring drinking water safety and quality
requires the application of a considered
risk management approach…
This requires steering a sensible course
between the extremes of failing to act when
action is required and taking action when
none is necessary.”
Australian Drinking Water Guidelines (National Health & Medical Research Council, 2011)
• Risk management is de rigueur in Australia for managing drinking water quality, and this is
legislated in many Australian jurisdictions
• Opportunity exists to embed climate adaptation risk processes into existing drinking water quality
management planning requirements
• Advantages are that authorities can address multiple planning and operating needs in one activity
and it contextualises the climate risks to impacts on tangible water quality objectives
• Appreciate that both climate change and water quality risk management guides already
incorporate similar principles from the ISO 31000:2009 Risk Management standard
Water quality risk management in a changing climate
Presentation overview:
• Review of potential water quality and public health impacts
• Describes common components of water quality and climate change risk management
frameworks
• Addressing challenges for integrating the approaches
• Framework and information needs for addressing climate change within existing drinking water
quality risk management plans
Water quality risk management in a changing climate
Projected trends in NSW:
• Reduced long-term rainfall
perhaps with more intense
storm events
• Higher evaporation
• Diminished stream flow
• More prolonged droughts
• Exacerbate the characteristics
of the land of “drought and
flooding rains”
Water quality impacts of variable climate
Refer to:
Commonwealth Scientific and Industrial Research Organisation and Australian Bureau of Meteorology (CSIRO &
BoM), 2007, Climate change in Australia: Technical Report 2007, Australian Government, Canberra, Australia.
NSW Department of Environment, Climate Change and Water, 2010, NSW Climate Impact Profile, accessed 10 June
2012 at http://www.environment.nsw.gov.au/resources/climatechange/10171climateimpactprof.pdf
Potential impacts on drinking
water quality* (catch-to-tap):
• Reviews generally describe a
degrading trend if not managed
• Dissolved organic matter,
micropollutants and pathogens
may present greater
challenges
• Sea-level changes can affect
groundwater quality
• May impact treatment
efficiency and needs
Water quality impacts of variable climate
*For example:
Delpla et al; 2009, ‘Impacts of climate change on surface water quality in relation to drinking water production’, Environment International, 35:1223-1233 [NB: The figure on
this slide is Figure 1 from this article]
Hunter, P; 2003, ‘Climate change and waterborne and vector-borne diseases’, Journal of Applied Microbiology, 94:37S-46S
Cromwell, et al. (2010), ‘Implications of climate change for urban water utilities’, Association of Metropolitan Water Agencies, Washington DC. Accessed 10 June 2012 at
http://www.amwa.net/galleries/climate-change/AMWA_Climate_Change_Paper_12.13.07.pdf
Water Services Association of Australia; 2012, Climate Change Adaptation and the Australian Urban Water Industry, Occasional Paper #27
Risk frameworks for water quality & climate management
Risk Management Step (ISO 31000:2009)
Context setting
Risk identification
Risk analysis
Risk evaluation
Risk treatment
Monitor and review
Consult
Framework for drinking water quality, from the Australian Drinking Water Guidelines, NHMRC, 2011
Draft framework for climate change adaptation decision-making for
infrastructure, from DR AS 5334 (draft open for public comment)
Water quality risk management is aimed at
ensuring safe and reliable water supplies...
In a variable climate, these same objectives
will still need to be met. It is useful to frame
risks not so much as being from climate, but
to the water quality, public health and the
authority
Risk frameworks for water quality & climate management
Risk Management Step
(ISO 31000:2009)
Applied to Drinking Water Quality
Management
Considering a Changing Climate
Context setting Set water quality objectives and commit to
meeting them
The same objectives and commitments
are required
Risk identification Identify hazards, their sources, and
how/what influences their presence in the
system
Would projected changes in temperature,
rainfall, etc. impact on hazard source
types, quantities or propagation?
Risk analysis Determine how effectively current hazard
controls operate, and assess the risk
based on likelihoods and consequences
associated with customer exposure to
hazards
Would projected changes in temperature,
rainfall, etc. impact on the effectiveness or
overwhelmingly challenge the current
controls?
Risk evaluation Take stock of what is driving the
assessed risk: inherent conditions,
variability or information gaps/uncertainty?
Re-evaluate the level of risk that may
ensue under a changing climate: can the
system cope with the scenarios?
Risk treatment Operate, monitor and verify the controls.
Investigate uncertainties to better
understand risks
Accommodate or plan to develop
indicators of, watch for and respond to
the changes
Monitor and review Is the plan working? Were the tested scenarios relevant and
informative? Consider the latest science
and observations
Risk frameworks for water quality & climate management Describing the system, identifying hazards, and conceptualising risks to drinking-water quality
Risk frameworks for water quality & climate management
RISK = Consequence
Lik
elih
oo
d
x 1 2 3 4 5
1 Low Low Medium High High
2 Low Low Medium High Very High
3 Low Medium High Very High Very High
4 Medium High High Very High Very High
5 Medium High Very High Very High Very High
R2 = 0.1428
0
1
2
3
4
5
6
7
8
9
10
0.001 0.01 0.1 1 10 100
Average flowrate (m3/s)
oo
cysts
/ L
Baseflow
Runoff
Assessing and evaluating risks associated with meeting drinking water quality objectives – common approach
0
1
2
3
4
5
A B C n = 12 n = 12 n = 12
Tot. coliforms – measured log reductions
* Charts based on
data from real
drinking water
catchments and
treatment plants,
reported in Signor, R;
2007, Probabilistic
Microbial Risk
Assessment and its
management
implications for
Urban Water Supply
Systems
** Risk matrix
provided in the
2011Australian
Drinking Water
Guidelines
Evaluate risk based on effectiveness of all controls,
and further manage accordingly**
Understand the sources and drivers of hazard presence*
Understand control efficacy*
Evaluate risk based on understood impacts and
responses
Risk frameworks for water quality & climate management
RISK = Consequence
Lik
elih
oo
d
x 1 2 3 4 5
1 Low Low Medium High High
2 Low Low Medium High Very High
3 Low Medium High Very High Very High
4 Medium High High Very High Very High
5 Medium High Very High Very High Very High
R2 = 0.1428
0
1
2
3
4
5
6
7
8
9
10
0.001 0.01 0.1 1 10 100
Average flowrate (m3/s)
oo
cysts
/ L
Baseflow
Runoff
Assessing risks associated with meeting drinking water quality objectives – example of re-evaluation for a changing climate
0
1
2
3
4
5
A B C n = 12 n = 12 n = 12
Tot. coliforms – measured log reductions
Understand the sources and drivers of hazard presence
Understand control efficacy
E.g. Disinfection efficacy is related to
water temperature (among other
things)
An average 5ºC increase in surface
water temperature can benefit
disinfection** (provided turbidity
stays low)
E.g. High rain/runoff events drive
pathogen loads entering the
reservoir
How might more frequent high
intensity runoff events challenge
the existing treatment and
controls?*
Re-evaluate under the described climate scenario:
• What’s the net change in risk?
• Would it become intolerable?
• What should be monitored to establish baselines
and extents of change over time?
• What can be done now to prepare should some
extent of climate change ensue?
RISK = Consequence
Lik
elih
oo
d
x 1 2 3 4 5
1 Low Low Medium High High
2 Low Low Medium High Very High
3 Low Medium High Very High Very High
4 Medium High High Very High Very High
5 Medium High Very High Very High Very High
* NSW planning advice is to assume intensity of rainfall events with some average recurrence interval (e.g. 1 in 10, 1 in 100 years, etc.) estimated from Australian Rainfall &
Runoff (Engineers Australia, 1987) may increase by up to 30% (New South Wales Department of Environment, Climate Change and Water; 2007, New South Wales
Floodplain Risk Management Guideline, Residential Flood Damages). The chart demonstrates implications for 72-hour rainfall events for a coastal region near Sydney.
** Chart demonstrates improvement in disinfection by assuming a 5ºC increase in water temperature at a water treatment plant in South Australia (assuming all other
parameters remain constant). Figures derived by applying probabilistic modelling techniques and assuming continuous stirred tank reactor conditions.
Risk frameworks for water quality & climate management Raw water storage – responses to climate and variable inflow conditions (a storage in the Murrumbidgee catchment)
Challenges incorporating climate change
1. What climate scenarios and timeframes are relevant to use?
2. Understanding impacts of changes on water quality hazards, and
implications for likelihood and consequence
3. Timeframes for actions, decisions under uncertainty and continuous
change
Challenges incorporating climate change
1. What climate scenarios and timeframes are relevant to use?
• As drinking water quality compliance is assessed over annual
timeframes, use relevant, near-term projections (link to strategic
planning horizons)
• Useful to consider extreme changes for the purpose of overlay on
current assessment techniques: this can help to rule out non-
material risks…
… planning needs to balance scenario assumptions vs. response to
changes that arise over time
Challenges incorporating climate change
2. Understanding impacts of changes on water quality hazards, and
implications for likelihood and consequence:
• Workshops
• Models
• Scenario assessments
Further reading: Jones & Preston (2010); Adaptation and Risk Management, Climate Change Working Paper #15, Centre for Strategic Economic Studies, Melbourne
University. Accessed 12 July 2012 at http://www.cfses.com/documents/climate/15_Jones_&_Preston_Adaptation_and_Risk_Management_2010.pdf
Challenges incorporating climate change
3. Timeframes for actions, decisions under uncertainty and continuous
change:
• Develop monitoring informed by risk assessment to examine
baseline vs. future conditions
• Determine thresholds for action based on observations
• Plan now so to be able to act swiftly to changes or specific events if
necessary
Further reading: Fisk, G., & Kay, R, (2010) ‘Dealing with Uncertainty in Climate Change Adaptation Planning and Developing Triggers for Future Action’, Proceedings
Practical Responses to Climate Change National Conference, 29 Sep – 1 Oct 2010, Melbourne.
Framework for considering climate changes
Examples of practical adaptation
planning outcomes for water utilities:
• Model changes to pathogen catchment
loads under longer dry periods, higher
intensity rain conditions
• Establish water temperature and N.
Fowleri (a “warm water pathogen”)
monitoring program
• Assessment of treatment capability
against manganese, iron and
cyanobacteria spikes – develop
protocols for dealing with extreme
challenges
• Develop thresholds and monitor
organic content in raw water to
manage THMs
• Survey community tolerance and
resilience against water supply with
higher salt content
Conventional Water Quality Risk
Management Process
Incorporating climate change impacts Identify hazards
Assess RISK
Monitor, manage, review
Are aspects
of these
climate-
dependent?
Determine climate scenarios
(relate to planning horizons) Pathways - how do hazards
enter the system?
Controls – how are hazards
managed and how well?
Collate climate projection data
Re-assess RISK for relevant
hazards under different climate
scenarios
Determine planning priorities
Summary
1. Climate adaptation planning will be most effective when embedded into existing
organisational business and process
2. Risk management is prescribed for drinking-water quality and climate adaptation
planning; there’s an opportunity to embed them within core water planning activities
3. Continue to focus on water quality objectives as the basis of risk management; this will
contextualise/simplify the climate assessments
4. Scenario based assessments of impacts of climate change on source and treated water
quality are the most useful ways to identify possible future risks and to start planning for
them
5. Models and geographically downscaled climate projections will be needed to assist with
understanding future risks; pre-emptive monitoring and planning will keep authorities
ready to respond to changes
Footnote
This presentation is based on preliminary findings of a study to be reported in
Signor, R. S; 2012, ‘Drinking water quality risk management in Australia: accounting for a
variable climate’, in preparation
www.ghd.com