Developing Tools to Enable

Water Resource Managers to

Plan for & Adapt to Climate

Change

Amy Snover, PhDClimate Impacts Group

University of Washington

July 2, 2004SICCIA

Climate Science in the

Public Interest

Introduction

• Despite uncertainties in climate change projections– PNW water resources clearly vulnerable over next few decades– Many PNW water resources managers now recognize importance of planning for climate change

• Academic climate change impact assessments tend to be “interesting but irrelevant” to resource managers

• Need for future streamflow scenarios that could be easily and inexpensively used within existing planning frameworks

Academic Research

Resource Management

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Somewhat wetter winters and perhaps somewhat drier summers

Projected PNW Climate Change

Main Impact: Less Snow

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Sensitivity of Water Resources

PNW water systems

• relatively little reservoir storage

• strong reliance on mountain snowpack

sensitive to changes in the seasonal pattern of streamflows

Timing of significant changes:

• ~20 years: hydrologic changes in rain/snow watersheds

• 40-50 years: hydrologic changes in snow-melt dominated systems

• Decades required to change water resources infrastructure or policy

PNW policy makers and water management agencies need to start planning for potential climate change now

1997-2001:

• Increasingly focused climate change research

• Intensive region-wide outreach

• Widespread official recognition of regional water resources systems’ lack of capacity to meet present & anticipated future demands even without climate change!

Planning for climate change

1997: First examination of PNW climate change impacts. Most stakeholders • unfamiliar with potential impacts of climate change • unprepared to use information

Out in Front: Portland & Seattle

Evaluating long-range planning alternatives under 5 different climate change scenarios (both supply & demand-side impacts)

1995: Interviews with natural resource managers

• Little recognition of predictability of climate • No framework for applying information about climate change

Stakeholders requested:• Climate change information for use in existing planning models• Case studies of incorporating climate change projections into

basin planning

Planning for climate change

2001 High level water policy workshop:• Climate change = potentially significant threat to regional water

resources • Climate change information = critical to future planning• Significant step forward!

Requirements of climate change information: • more detailed, small scale information (catchment, watershed)• must be “easy to apply to the problem at hand”

Observed Streamflows

Planning Models

System Drivers

Critical Period Planning Methods for Water Studies

Columbia River at The Dalles

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192519251925192619261927192719271928192819291929193019301930193119311932193219321933193319341934

Long-Range Water Resources Planning

How would the water resources system respond to the drought of the 1930s with the current/alternate reservoir operating policy?

Observed Streamflows

Climate Change Scenarios

Planning Models

Altered Streamflows

System Drivers

Incorporating Climate Change in Critical Period Planning

What would water year X mean for our water resources system if the average climate changed as projected?

Climate change streamflow scenario development

• Four GCM climate change scenarios (2020s & 2040s)

• Downscaled to PNW using “delta method”– Perturb gridded historical meteorological data by

monthly projected ∆T and ∆p– Retains fundamental temporal and spatial

variability of observed regional climate and chronological sequencing of observed flows

• Simulate 40 year time series of monthly streamflows using hydrologic model

• Remove hydrologic model bias via probability mapping

Distributed hydrology model (VIC)

Monthly changes in mean temperature and precipitation from global climate models

Observed time series of meteorological data (gridded)

Removal of hydrologic model bias using probability mapping

Climate change streamflow scenarios

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QuickTime™ and aTIFF (LZW) decompressor

are needed to see this picture.

Application of Scenarios

• Tailored for use by– Northwest Power Planning Council

(regional hydropower resources)– Idaho Department of Water

Resources (irrigation)

• Publicly available via web server

• Portable method can be applied to other users

Planning for Climate Change: Future streamflow scenarios

Water policy workshops have highlighted the need to inject climate change information into existing river basin planning activities and to provide free access to streamflow scenarios.

www.cses.washington.edu/cig/ … see “Forecasts and Planning Tools”Snover et al. BAMS 2003

Conclusions

• Despite uncertainty in climate change projections, PNW water resources likely to experience important impacts within a few decades

• Initial outreach efforts (“describing & exhorting”) had some success– Potential impacts are well recognized– Shift in dialogue from what will happen to how to plan for it

• Without additional effort by academics to develop useful tools, region not likely to progress beyond a cursory examination of climate change

• Climate change streamflow scenarios (produced by perturbing the observed historical streamflow record) can be easily and inexpensively used in existing planning processes

– Intent is to enable rapid injection of climate change information to support vulnerability assessment

– First step towards more sophisticated assessments– Provides a “road map” for other agencies

For More Information …

UW Climate Impacts Group

www.cses.washington.eduwww.cses.washington.edu

Climate Science in the

Public Interest