Generating a Comprehensive Climate Change Streamflow Scenarios Database for the Columbia River Basin Alan F. Hamlet Kurt Unger Philip W. Mote Eric Salathé Dennis P. Lettenmaier JISAO/CSES Climate Impacts Group Dept. of Civil and Environmental Engineering University of Washington WA State Department of Ecology

Image Credit: National Snow and Ice Data Center, W. O. Field, B. F. Molnia Aug, 13, 1941Aug, 31, 2004 Recession of the Muir Glacier

March 5, 2002 Collapse of the Larsen B Ice shelf, Antarctica

Mote P.W.,Hamlet A.F., Clark M.P., Lettenmaier D.P., 2005, Declining mountain snowpack in western North America, BAMS, 86 (1): Trends in April 1 SWE

Overview of 21 st Century Climate Projections and Some Water Resources Impact Pathways

Pacific Northwest °C °C °C °C Observed 20th century variability +1.7°C +0.7°C +3.2°C

Pacific Northwest % -1 to +3% -1 to +9% -2 to +21% Observed 20th century variability +1% +2% +6%

Simulated Changes in Natural Runoff Timing in the Naches River Basin Associated with 2 C Warming Impacts: Increased winter flow Earlier and reduced peak flows Reduced summer flow volume Reduced late summer low flow

Water Supply and Demand Changes in the seasonality water supply (e.g. reductions in summer) Changes in water demand (e.g. increasing evaporation) Changes in drought stress Increasing conflicts between water supply and other uses and users of water Energy Supply and Demand Changes in the seasonality and quantity of hydropower resources Changes in energy demand Increasing conflicts between hydro and other uses and users of water Instream Flow Augmentation Changes in low flow risks Changes in the need for releases from storage to reproduce existing streamflow regime. Changes in water resources management related to water quality (e.g. to provide dilution flow or to control temperature)

Flood Control and Land Use Planning Changes in flood risks Changes in flood control evacuation and timing Dam safety Impacts in Estuaries Impacts of sea level rise and changing flood risk on low lying areas (dikes and levies) Impacts to ecosystem function Changes in land use policy (coastal armoring, land ownership, FEMA maps) Long-Term Planning, Water Resources Agreements, Water Law and Policy Water allocation agreements in a non-stationary climate (e.g. water permitting) Appropriateness of the historic streamflow record as a legal definition of climate variability Need for new planning frameworks in a non-stationary climate Transboundary implications for the Columbia Basin

As the public and professionals in the water management and policy arenas have become increasing concerned about the impacts of climate change on PNW water resources, demand for hydrologic scenarios suitable for planning purposes at a range of spatial scales has increased dramatically. Currently there does not exist an up-to-date, comprehensive, and self-consistent data base of hydrologic scenarios for the Columbia River basin that is suitable for the range of planning activities the Climate Impacts Group is being asked to support. A Need to Provide Improved Access to Hydrologic Scenarios for Planning

Study Overview

Collaboration with WA Department of Ecology and Regional Stakeholders to Provide Improved Access to Hydrologic Scenarios in the Columbia River Basin Funding Source: House Bill 2860 $16 Million for studies related to enhancing water supplies in the Columbia River basin for irrigation and municipal water supply. Up to $200 Million for implementing improvements identified by these studies. Answers to FAQ regarding WA 2860 from the Department of Ecology website:

Regional Study Partners WA State Department of Ecology Bonneville Power Administration Northwest Power and Conservation Council State of Oregon Province of British Columbia (BC Hydro and The Ministry of Environment)

Streamflow Data Needs to Support a 21 st Century Planning Framework Incorporating Climate Information and Uncertainty 2 Emissions Scenarios 20 GCM Scenarios 2 Downscaling Approaches X X 2 Hydro. Modeling Approaches X = Up to 160 realizations of future streamflow variability at each location!

The Need to Encompass Multiple Spatial Scales

Large Scale Planning Studies Examples: Hydro System Performance Flood Control Main Stem ESA Transboundary Issues Large-Scale Irrigation Impacts

WA State Water Resources Inventory Areas Medium Scale Planning Studies Examples: Water Supply Planning Yakima Basin Okanogan Basin Methow Walla Walla Basin

Snow Model Schematic of VIC Hydrologic Model and Energy Balance Snow Model PNW 1/16 th Deg. 6 km

Alternate Approach: DHSVM Developed in the UW Land Surface Hydrology Research Group at UW, the model has been used for over a decade in hydrologic research applications associated with small catchments. DHSVM: Distributed Hydrology-Soil- Vegetation Model

Blue = Large Scale Planning Sites Green = Snake River Sites Red = Additional Sites in WA Partnerships with the BPA, NWPCC, OR and BC will extend the number of sites included in the study to support specific planning activities in these areas. The UW will also collaborate informally with the U of I. Streamflow Locations Currently Under Consideration

On-Line Survey Website, Project Scope