Future Water Demand in light of

uncertainty regarding climate

change

Presented by Ben Piper, Technical Director (Atkins)

On behalf of original CC:DEW project team:

Tom Downing (GCAP)

Keith Weatherhead &

Jerry Knox (Cranfield)

2

The demand planner is:

• catering for the needs of age cohorts not yet born

• in a climate not yet experienced

• within government policies not yet thought of

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5 Tariff Changes:

January 1990

May 1990

Tariff change - December

Penalties Penalties Lifted

Population Projection Results

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1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

2008 2010 2012 2014 2016 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036

Year

Popula

tion, per

sons

Logistic System Model (Logistic 模型) Grey System Model (灰度模型)

Linear Regression Model (线性回归模型) GDP (Likely Scenario) (GDP 模型 - 可能性较高的)

Outline of Presentation

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CC:DEW study: recap and application of results

What has changed since then?

What are the future challenges?

Gaps for researchers and practitioners: uncertainty in adaptive management

CC:DeW - recap

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Starting point (July 2000):

● Review of Herrington 1996

● UKCIP ‟98 climate scenarios

● Environment Agency Foresight-based Demand Scenarios

Components of demand

● Domestic

● Industrial/Commercial

● Agriculture (crop production)

Excluded from ToR

● Leakage

● Peak demands

● Stacking of droughts

● Extreme events

Scope of CC:DeW

5

Socio-economic driving forces

(EA Foresight Scenarios):

- Demography

- Economy

- Land use

- Culture

- Infrastructure

Policy:

- Regulation

- Investment

- Environment (abstraction)

- European water directive

Stakeholder decision making:

- Business strategy

- Attitudes toward risk

- Planning guidelines

Climate system:

- Mean changes

- Variability

- Extremes

- Scale

RESOURCES

DEMAND SUPPLY

SUPPLY/DEMAND BALANCE

- Scarcity

- Risk

- Uncertainty

RESPONSES

Climate Change Scenarios

- UKCIP 1998

- UKCIP 2002

CC:DEW results

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Uptake

• Water Resource Plans

• Periodic Reviews: PR04, PR09

• EA Water Resource Planning Guideline open to different interpretations

• Guided agricultural water resources management

Traditional approach

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Historic Timeseries: Rainfall, ET Flow, GW Level

Demand

Surface Water

DO

Rainfall-Runoff

River Flows

Groundwater

DO

Recharge

GW Level

> + Supply Target

Headroom

Demand

Conjunctive Use

DO

WR System Model

Headroom (including Climate

Change)

Deterministic Supply-Demand

Balance

CC:DEW results

8

Shortcomings

• Only covered average demands, not peak

• Considered by practitioners to be relatively crude derivation and application of factors

• Low spatial resolution

• Covered England & Wales

• Ignored CO2 impacts on crop production

CC:DeW - Agent based modelling

Aggregate demand series scaled so 1973=100

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Simulation Date

Re

lative

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ma

nd

Climate change impacts

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AlphaMH

BetaMH

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DeltaMH

Agent based:

Discontinuities

Large range of results

Dynamic simulation:

Smooth scenarios

Modest range

Next steps – articulated at end of

CC:DEW

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Limitations

● Variability and drought risk

● Low confidence in scenarios for 2020s

● Present data sets

● Behavioural change: technology, demand management

Toward the next assessment

● Integrate supply/demand balance

● Incorporate human behaviour in dynamic scenarios

● Continue data collection and monitoring

● Probabilistic scenarios of climatic risks

● Incorporate uncertainty into demand projections

● Consider CC impacts on resource availability

Recap on UK Water Industry Research

AMP Period Period covered

Climate change

scenarios Notes

1 1990-1995 Generally not considered

2 1995-2000 UKCIP98 UKWIR CL04 1997

Recalculation of flow factors

Herrington

3 2000-2005 UKCIP02 UKWIR CL04 2002

EA WRPG Ver 3.3 (2003)

CC:DEW

4 2005-2010 Catchment level assessments

CC uncertainty in WR Planning

Trends in UK River Flows

Strategy for evaluating uncertainty in assessing

CC impacts on Water Resources

Interim report on R-Q modelling

5 2010-2015 UKCP09 New methods based on UKCP09

Future challenges

12

Scenarios of water risk

Demand analysis

Integrating supply and demand

Behavioural responses

Spatial scale of influences on demand

Scenarios of risk need to capture the

uncertainty in water planning

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Define relevant climate variables and parameters: problem of joint distributions

Include worst case „what if‟ futures

Unpack confidence in various time scales

1 10 100 1000 10000 100000

Weather forecasts

Seasonal outlooks

Decadal dynamics

GHG forced GCM

DAYS

Demand-side analysis lags behind

supply-side analysis

14

Very few recent articles

● Vorosmarty et al. 2000: global non-climate demand

● Dessai and Hulme 2007: climate focus, not demand

● Wilby et al. 2006: supply focus, gaps identified

● Subak, 2000: managers‟ perceptions, supply focus

Retrospectives of past events – response to 2005-2006 drought in SE England

Should be more data available, and accessible to explore sensitivity of demand to climate variations

Integrating supply and demand to

develop robust response strategies

Supply-demand balance rather than separate assessments

Presenting complex information to stakeholders for public understanding

Responses on the time scale of climate change are

essentially behavioural

Ind

ivid

ual

So

cia

l

Reference runs MH climate change

CCDew looked at how behaviour might change along with climate change. Results of an agent-based

social simulation model show the diversity of water demand scenarios. The model compares the role

of social pressure compared to individual decision making (top and bottom) and with and without

climate change (left and right). The scenarios broadly correspond to the earlier EA reference

scenarios: individual (alpha and beta); social (gamma and delta).

Future agricultural demand

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Projections influenced by assumptions regarding population growth, food demand and patterns of food consumption

In reality, future demand will be influenced by actual water availability and allocation policy

New cultivars, genetic improvements, and effects of elevated CO2 could significantly offset future increases in water demand

But the regulator and consumers (supermarkets) will demand better management, uptake of new technologies and innovative approaches to water scarcity (such as water trading)

Adaptation in agricultural irrigation

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There will be some autonomous adaption but growers will need to build adaptive capacity to cope with extremes and uncertainty

Many potential adaptations (e.g. reservoirs) are „no regret‟ -they already make sense by solving existing water resource issues, which then contribute to a farms future adaptability

But most growers remain more concerned about „non-climate‟ risks particularly very high degree of short- to medium-term uncertainty in agricultural policy and markets

Return to UK PWSPlanning

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• 5 year cycle of Periodic Review focussed on public water supply

• Analysis has tended to be limited to the boundaries of individual Water Resource Zones, but increasing interest in cross WRZ transfers

• Uncertainty and risk tend to have been treated as add-ons in supply-demand balance analysis

• Impacts on agriculture sector not just on irrigation water requirements, but also on food security

Socio-economic driving forces

(EA foresight scenarios)

Policy:

-Regulation

- Investment

- Environment (abstraction)

- European water directive

Stakeholder decision making:

-Business strategy

-Attitudes toward risk

-Planning guidelines

Climate Change Scenarios

-UKCIP 1998

-UKCIP 2002

RESOURCES

DEMAND SUPPLY

SUPPLY/DEMAND BALANCE

-Scarcity

-Risk

-Uncertainty

Climate system

-Mean changes

-Variability

-Extremes

-Scale

RESPONSES

Socio-economic driving forces

(EA foresight scenarios)

Policy:

-Regulation

- Investment

- Environment (abstraction)

- European water directive

Stakeholder decision making:

-Business strategy

-Attitudes toward risk

-Planning guidelines

Climate Change Scenarios

-UKCIP 1998

-UKCIP 2002

- UKCP09

RESOURCES

DEMAND SUPPLY

SUPPLY/DEMAND BALANCE

-Scarcity

-Risk

-Uncertainty

Climate system

-Mean changes

-Variability

-Extremes

-Scale

RESPONSES

Need for more integrated approach?

22

Stochastic

Demand

Climate

Change

Uncertainty

Stochastic Supply-

Demand Balance

P P P

UKCP09 Weather Generator

Rainfall PET Temperature

P

Headroom

(other

uncertainties)

Groundwater

DO

Recharge

GW Level

Surface Water

DO

Rainfall-Runoff

River Flows

Conjunctive Use DO

WR System

Model

Risk Based Target

Headroom

Discussion

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Research Agenda

Development of “Best Practice” approach, acceptable to water utilities, regulators, customers, and other stakeholders

Extreme events

Next planning cycle coming soon

Future Water Demand in light of

uncertainty regarding climate

change

Presented by Ben Piper, Technical Director (Atkins)

On behalf of original CC:DEW project team:

Tom Downing (GCAP)

Keith Weatherhead &

Jerry Knox (Cranfield)