Water Management and Climate Change in the US-

Mexico Border Region

Robert LempertSenior Scientist

RAND

September 27, 2008

climate -2

Climate Change Poses Significant Challenge for Resource Planning the US-Mexico Border Region

• “Stationarity is dead” – Many organizations already include climate (often implicitly) in

their decisions – Amidst all the uncertainty one thing we do know for sure --

tomorrow’s climate will not be like the past’s

• Changes in West are likely to include:– Increased temperatures– Changes in precipitation patterns– More intense storms– Declining snow pack and summertime river flows

• Without proper planning:– Supply expectations may not be met– Demand may grow faster than can be accommodated– Infrastructure may fail

climate -3

Planners in S. California, for Instance, Face aRange of Possible Future Climate Conditions

Summer-time temperature change(2000- 2030)

+.1C +2.1C0

Likely range

Results based on statistical summary of 21 of the world’s best Global Climate Models

No change Hotter

Wetter

Winter-time precipitation change (2000 - 2030)

+8%-19% 0

Likely rangeMuch drier

Water managers also face many similar, if not more, disruptive uncertainties

climate -4

Our Work With California Water Agencies Suggests Lessons for US-Mexico Border Region

• Resource managers can no longer assume future climate will be like the past

• Despite deep uncertainty, sufficient information exists to support prudent action today

• Effective response options are available

• Legislatures may have to help ensure:– Access to appropriate data and information

– Funding for demonstration projects and new infrastructure

– Appropriate incentives and perhaps some regulatory changes

climate -5

Conducted Vulnerability and Options Analysis for Inland Empire Utilities Agency (IEUA)

– IEUA currently serves 800,000 people

• May add 300,000 by 2025– Water presents a significant

challenge

climate -6

– Current water sources include:

• Groundwater 56%• Imports 32%• Recycled 1%• Surface 8%• Desalter 2%

Conducted Vulnerability and Options Analysis for Inland Empire Utilities Agency (IEUA)

– IEUA currently serves 800,000 people

• May add 300,000 by 2025– Water presents a significant

challenge

climate -7

– Current water sources include:

• Groundwater 56%• Imports 32%• Recycled 1%• Surface 8%• Desalter 2%

Focus of IEUA’s 20 year plan

Conducted Vulnerability and Options Analysis for Inland Empire Utilities Agency (IEUA)

– IEUA currently serves 800,000 people

• May add 300,000 by 2025– Water presents a significant

challenge

climate -8

Our Research Focused on Two Key Questions

• Are IEUA’s plans vulnerable to assumptions about uncertain future conditions, including climate change?

• Which actions should IEUA do now and which can they defer to later to address the threat of climate change?

climate -9

We Identified Three Types of Assumptions That Could Impact the Performance of IEUA Plans

• Imported supplies• Water use efficiency

Costs of Future Supplies and Management Activities

• Development of aggressive waste-water recycling program

• Implementation of groundwater replenishment

Performance of Management Strategies

• Future temperatures• Future precipitation• Changes in groundwater processes

Natural Processes

climate -10

We Identified Three Types of Assumptions That Could Impact the Performance of IEUA Plans

• Imported supplies• Water use efficiency

Costs of Future Supplies and Management Activities

• Development of aggressive waste-water recycling program

• Implementation of groundwater replenishment

Performance of Management Strategies

• Future temperatures• Future precipitation• Changes in groundwater processes

Natural Processes

climate -11

We Identified Three Types of Assumptions That Could Impact the Performance of IEUA Plans

• Imported supplies• Water use efficiency

Costs of Future Supplies and Management Activities

• Development of aggressive waste-water recycling program

• Implementation of groundwater replenishment

Performance of Management Strategies

• Future temperatures• Future precipitation• Changes in groundwater processes

Natural Processes

climate -12

IEUA Faces a Wide Range of Possible Future Climate Conditions

Summer-time temperature change(2000- 2030)

+.1C +2.1C0

Likely range

No change Hotter

Wetter

Winter-time precipitation change (2000 - 2030)

+8%-19% 0

Likely rangeMuch drier

climate -13

Model Performance of plans

IEUA Plans

System data & climate forecasts

Our Simulation Model Assessed Performance of IEUA Plans in Different Future States of World

Temp: +1.6Temp: +1.6ooC Precip: -10%C Precip: -10%

Scenario BPlan suffers shortages in adverse future climate

005050

100100150150200200250250300300350350400400

20052005 20102010 20152015 20202020 20252025 20302030YearYear

Ann

ual s

uppl

y (ta

f)A

nnua

l sup

ply

(taf)

RecycledRecycled

GroundwaterGroundwater

Local SuppliesLocal Supplies

ImportsImports

Dry-year yieldDry-year yieldSurplusSurplus

ShortageShortage

Temp: +0.7Temp: +0.7ooC Precip: +3%C Precip: +3%

Scenario APlan generates surpluses in benign future climate

005050

100100150150200200250250300300350350400400

20052005 20102010 20152015 20202020 20252025 20302030YearYear

Ann

ual s

uppl

y (ta

f)A

nnua

l sup

ply

(taf)

RecycledRecycled

GroundwaterGroundwater

ImportsImportsSurplusSurplus

Local SuppliesLocal Supplies

climate -14

IEUA’s Ability to Implement Its Plan and The Agency’s Future Costs are Also Uncertain

• Estimates of agency’s likelihood of achieving its recycling and ground water goals

• Future costs of alternative sources of supply

0 250 500 750 1,000 1,250 1,500

Saved through efficiency

Recycled

Storm-water replenishment

Groundwater

Recycled replenishment

Imported (Tier 1)

Imported replenishment

Imported (Tier 2)

Desalted groundwater

Shortages

Cost component

Levelized costs for 2005 and 2015 ($ per af)

1,860

climate -15

Simulation Suggests that Climate Change Exacerbates Other Risks to IEUA’s Plan

Factors consideredPerformance towards recycling goalPerformance towards replenishment goalFuture climateAmount of new conservationAmount of groundwater infiltrationEffect of climate on imports

Ran simulation 1,000 times for many different

combinations of uncertain factors

In 656 cases IEUA’s plan has low cost

In 344 cases IEUA’s plan has high cost

What factors explain these high cost cases?

Key Vulnerabilities to IEUA PlanMiss recycling goal

Adverse future climate

Any reduction in groundwater infiltration

climate -16

Our Research Focused on Two Key Questions

• Are IEUA’s plans vulnerable to assumptions about uncertain future conditions, including climate change?

• Which actions should IEUA do now and which can they defer to later to address the threat of climate change?

climate -17

Response Options May Help IEUA Address These Vulnerabilities

• Efficiency reduces demand but imposes costs on customers and requires customer participation

• Improved groundwater management increases resilience to shortages but requires significant cooperation and faces unknown costs

• Recycled water use is a drought-proof supply but requires significant public support

Each Option Has Benefits and Costs

climate -18

Should IEUA Act Now or Later to Reduce Potential Climate Vulnerabilities?

Act now to Act now to augment augment

2005 Plan?2005 Plan?

NO

Monitor, and take Monitor, and take additional action if additional action if supplies drop too supplies drop too

lowlow

In 2015, 2020, 2025, ….

YESImplement Implement additional additional efficiency, efficiency,

recycling, and recycling, and replenishmentreplenishment

In 2015, 2020, 2025, ….

Monitor, and take Monitor, and take additional action if additional action if supplies drop too supplies drop too

lowlow

climate -19

We Evaluated Nine Strategies Under200 Scenarios Reflecting Key Uncertainties

Number of Scenarios (PV Costs > $3.75 billion)0 40 8060 100 12020

Current Plan Forever

UWMP + DYY and recycling

UWMP + replenishment

UWMP with updates

UWMP + replenishment with updates

UWMP + efficiency

UWMP + efficiency with updates

UWMP + DYY and recycling with updates

UWMP + all enhancementsStatic optionsUpdate options

climate -20

Just Allowing the Current UWMP to UpdateReduces Vulnerability Substantially

0 40 8060 100 12020

Static optionsUpdate options

From 120Down to 30

Number of Scenarios (PV Costs > $3.75 billion)

Current Plan Forever

UWMP + DYY and recycling

UWMP + replenishment

UWMP with updates

UWMP + replenishment with updates

UWMP + efficiency

UWMP + efficiency with updates

UWMP + DYY and recycling with updates

UWMP + all enhancements

Still vulnerable to:• Precipitation declines• Declines in imports • Costs of imports

climate -21

Implementing Efficiency and Other Options NowReduces Future Vulnerabilities Even More

0 20 403010

Static optionsUpdate options

Number of Scenarios(PV Costs > $3.75 billion)

UWMP with updates

UWMP + replenishment with updates

UWMP + efficiency

UWMP + efficiency with updates

UWMP + DYY and recycling with updates

UWMP + all enhancements

Implementation becomes

more challenging

climate -22

Implementing Efficiency and Other Options NowReduces Future Vulnerabilities Even More

0 20 403010

Static optionsUpdate options

Number of Scenarios(PV Costs > $3.75 billion)

UWMP with updates

UWMP + replenishment with updates

UWMP + efficiency

UWMP + efficiency with updates

UWMP + DYY and recycling with updates

UWMP + all enhancements

IEUA should make more near-term efficiency investments; monitor performance and adapt as needed down the road

Implementation becomes

more challenging

climate -23

US-Mexico Border Region Can and Must Begin Adapting to Climate Change

• Resource managers can no longer assume future climate will be like the past

– Impacts of climate change may create significant vulnerabilities in agencies’ operations and plans

• Despite deep uncertainty, sufficient information exists to support prudent action

– New planning methods may prove necessary

– Key is identifying near-term actions that are robust over a wide range of plausible futures

• Effective response options are available– Inland Empire Utilities Agency should increase investment in near-

term conservation, monitor carefully, and prepare to take further actions

– Other agencies may require additional near-term responses

climate -24

climate -25

Analysis Suggests Three Such Driving Forces

• Conducted statistical, cluster-finding analysis over all the model runs to identify the factors most strongly associated with shortages in 20 Year Plan

Meet recycling goal

Meet replenishment goal

Future climate

New conservation

Reduced groundwater infiltration

Climate on imports

Miss ExceedMeet

Miss ExceedMeet

Drier Wetter

-5% +20%

-20% 0%

Weak Strong

Explains 127 (of 180) low surplus cases

climate -26

Simulation Model Evaluated IEUA’s Current Plan Under Many Different Scenarios

IEUA WaterManagement

Options

Uncertainties

SimulationModel

OptionPerformance

climate -27

Scatter Plots Summarize Supply and Shortage Costs for Each Scenario for Current Plan

0 1.0 2.0 3.0 4.0PV shortage cost ($ billions)

2.5

3.0

3.5

4.0

PV supply cost

($ billions)

Current Plan Forever

climate -28

0 1.0 2.0 3.0 4.0PV shortage cost ($ billions)

2.5

3.0

3.5

4.0

PV supply cost

($ billions) Scenario A

• Modest warming and minimal precipitation decrease

• $3.3 billion in supply cost

• $0 in shortage cost

Current Plan Forever

Scenario B

• Significant warming and precipitation decrease

• $3.4 billion in supply cost

• $1.9 billion in shortage cost

Scatter Plots Summarize Supply and Shortage Costs for Each Scenario for Current Plan

climate -29

0 1.0 2.0 3.0 4.0PV shortage cost ($ billions)

2.5

3.0

3.5

4.0

PV supply cost

($ billions)

Current Plan Forever

(200 Scenarios)

Scatter Plots Summarize Supply and Shortage Costs for Each Scenario for Current Plan

climate -30

The Current Plan Performs PoorlyUnder Many Possible Future Conditions

0 1.0 2.0 3.0 4.0PV shortage cost ($ billions)

2.5

3.0

3.5

4.0

PV supply cost

($ billions)

Current Plan Forever

$3.75 billion cost threshold

(120 of 200 Scenarios)

climate -31

Statistical Analyses Suggested Three MajorVulnerabilities to the IEUA Plan

0 1.0 2.0 3.0 4.0PV shortage cost ($ billions)

2.5

3.0

3.5

4.0

PV supply cost

($ billions)

Current Plan Forever

$3.75 billion cost threshold

(120 of 200 Scenarios)

1. Strong declines in precipitation

2. Reductions in imported supply

3. Changes in groundwater replenishment