Strategies for Water Planning in an Uncertain Climate JISAO/SMA Climate Impacts Group and Department of Civil and Environmental Engineering University of Washington March, 2004 Alan F. Hamlet

People in the Climate Impacts Group PI: Edward L. Miles (human dimensions) Principals: Robert Francis (aquatic ecosystems) Dennis P. Lettenmaier (hydrology and water resources) Nathan Mantua (climate dynamics) Philip W. Mote (state climatologist) Lara Whitely Binder (education and outreach) Richard Palmer (water resources management) David L. Peterson (forests) Amy K. Snover (integration and synthesis)

Example of a flawed water planning study: The Colorado River Compact of 1922 The Colorado River Compact of 1922 divided the use of waters of the Colorado River System between the Upper and Lower Colorado River Basin. It apportioned **in perpetuity** to the Upper and Lower Basin, respectively, the beneficial consumptive use of 7.5 million acre feet (maf) of water per annum. It also provided that the Upper Basin will not cause the flow of the river at Lee Ferry to be depleted below an aggregate of 7.5 maf for any period of ten consecutive years. The Mexican Treaty of 1944 allotted to Mexico a guaranteed annual quantity of 1.5 maf. **These amounts, when combined, exceed the river's long-term average annual flow**.       

Education Outreach Partnerships CIG Stakeholders Planning Partnerships Seattle Public Utilities Portland Water Bureau Northwest Power and Conservation Council Idaho Dept. of Water Resources Demonstrate a long-term commitment and responsiveness (takes several years to develop interest and/or trust) Key stakeholders Federal: Bonneville Power Administration, Natural Resource Conservation Service, Army Corps of Engineers, Forest Service Tribal: Columbia River Intertribal Fisheries Commission, Northwest Intertribal Fish Comm. State: WA Depts of Ecology, Natural Resources, Fish & Wildlife; OR Dept of Lands (Coastal Mgmt), ID Dept of Water Resources Local: Seattle Public Utilities (Water), Seattle City Light, Portland Water Bureau

CIG Annual Water Workshops http://jisao.washington.edu/PNWimpacts/Workshops/Kelso2003/index.htm

Critical Period Planning Methods for Water Studies Observed Streamflows Planning Models System Drivers

Climate Change Scenarios Incorporating Climate Change in Critical Period Planning Long term planning for climate change may include a stronger emphasis on drought contingency planning, testing of preferred planning alternatives for robustness under various climate change scenarios, and increased flexibility and adaptation to climate and streamflow uncertainty. Observed Streamflows Planning Models Altered Streamflows Climate Change Scenarios System Drivers

Changes in Mean Temperature and Precipitation or Bias Corrected Output from GCMs ColSim Reservoir Model VIC Hydrology Model

The main impact: less snow VIC Simulations of April 1 Average Snow Water Equivalent for Composite Scenarios (average of four GCM scenarios) Current Climate 2020s 2040s Snow Water Equivalent (mm)

Naturalized Flow for Historic and Global Warming Scenarios Compared to Effects of Regulation at 1990 Level Development Historic Naturalized Flow Estimated Range of Naturalized Flow With 2040’s Warming Regulated Flow

Effects to the Cedar River (Seattle Water Supply) for “Middle-of-the-Road” Scenarios

Web-Based Data Archive http://www.ce.washington.edu/~hamleaf/climate_change_streamflows/CR_cc.htm

Climate Change May Exacerbate Other Impacts climate change and growth growth climate change Exceedance Probability of Reduced Storage Value from Current Climate and 2000 Demands

Climate change adaptation may involve complex tradeoffs between competing system objectives Source: Payne, J.T., A.W. Wood, A.F. Hamlet, R.N. Palmer and D.P. Lettenmaier, 2004, Mitigating the effects of climate change on the water resources of the Columbia River basin, Climatic Change (in press).

There may be thresholds associated with impacts Water supply timing changes estimated to occur by 2020 are handled by the storage and allocation system with little shortage change. However, the modeled reductions in water amount by 2040 would produce much more significant irrigation water shortages. These results could be made worse by changes in water demand.

Sources of Uncertainty

Problems with potentially biased spatial patterns in free running GCMs Do free running GCMs accurately reproduce the position of dominant storm tracks for particular regions? How far can GCM output be downscaled if the position of the storm track is unrealistic or biased? Snake gets wetter Snake gets drier Current Current Future Future

Effects of the PDO and ENSO on Columbia River Summer Streamflows PDO Cool Cool Warm Warm high high low low Ocean Productivity

Trends in Annual Streamflow at The Dalles from 1858-1998 are strongly downward.

The Dust Bowl was probably not the worst drought sequence in the past 250 years red = observed, blue = reconstructed Source: Gedalof, Z., D.L. Peterson and Nathan J. Mantua. (in review). Columbia River Flow and Drought Since 1750. Submitted to Journal of the American Water Resources Association.

Role of Monitoring in Scenario Validation

20th century decline in NH snow cover Surface measurements Satellite meas. Winter months show increases in snow cover Open diamonds are from surface measurements, closed diamonds from satellite meas. Brown, R.D., 2000: Northern Hemisphere snow cover variability and change, 1915-1997. Journal of Climate, vol 13. R.D. Brown, J. Climate, 2000

Trends in April 1 snow water equivalent, 1950-2000 Source: Mote et al. (2004)

Snowmelt runoff timing trends, 1948-2000 Graphic provided by Dan Cayan, Scripps Institute of Oceanography and the USGS. To appear in Climatic Change, 2003

Some Broad-Based Management Alternatives Supply Side Increase conventional storage Build new storage projects Enlarge existing storage projects Off-stream surface water storage projects Ground water storage and recharge Advanced waste water treatment systems (Yelm, WA) Reverse osmosis in coastal areas Improve forecasting systems and management Demand Side Conservation and plumbing codes Pricing of water to reflect scarcity and demand Market based transfers and water banks

Approaches and Criteria for Identifying Preferred Management Alternatives and Robust Planning Strategies 1) Identify the components of the planning process that are sensitive or insensitive to climate uncertainties 2) Identify planning alternatives that are acceptable and robust to different climate scenarios, even if they are perhaps not optimal under all climate scenarios 3) If no one plan is best under all climate scenarios, then identifying which plan is best for each scenario may be helpful in assessing the ability to respond to evolving conditions. 4) Identify alternatives that are more flexible than others in the sense that they can be substantially altered as uncertain conditions evolve. Such plans may be preferable if the water system is very sensitive to altered climate (and particularly uncertain projections of precipitation variability). 5) Identify plans that have "irreversible" components (e.g. because of investment in infrastructure or other capital expenditures). Such plans may in some cases increase future risks and reduce response capability. Identify "no regrets" strategies that create desirable outcomes regardless of uncertainties. (e.g. improve communication drought planning) Identify management alternatives or planning strategies that are “self tending” and evolve dynamically without recursive policy intervention. (e.g. water markets or water pricing mechanisms)

Selected References and URL’s Climate Impacts Group Website http://jisao.washington.edu/PNWimpacts/Infogate.htm White Papers, Agenda, Presentations for CIG 2001 Climate Change Workshop http://jisao.washington.edu/PNWimpacts/Workshops/Skamania2001/WP01_agenda.htm Climate Change Streamflow Scenarios for Water Planning Studies http://www.ce.washington.edu/~hamleaf/climate_change_streamflows/CR_cc.htm Refs on Climate Variability and Climate Change http://www.ce.washington.edu/~hamleaf/hamlet/publications.html