About TreeFlow

TreeFlow is a comprehensive web resource on tree-ring reconstructions of streamflow and climate for the western US, providing access to reconstruction data as well as information on data development and applications. While the primary users of streamflow reconstructions are water resource professionals, people in many other sectors and disciplines may find the data useful.

TreeFlow is intended to be a dynamic resource. We have designed the pages to be expanded as reconstructions are generated for other basins, and as new applications are developed. We welcome the contributions of other researchers and water providers. In the future, we also will include other hydrologic reconstruction resources, such as a network of Rocky Mountain snowpack reconstructions and North American monsoon reconstructions that are currently under development.

TreeFlow is a collaborative effort of researchers affiliated with three NOAA-funded Regional Integrated Sciences and Assessment (RISA) programs: Climate Assessment for the Southwest (CLIMAS) Western Water Assessment, and the Climate Impacts Group. The TreeFlow website is housed on a server at the University of Arizona.

Sections on this page:

• A Quick Tour of TreeFlow

• The TreeFlow Team and Support

• A Brief History of TreeFlow

• Assessment of Scientific Outreach Study

A Quick Tour of TreeFlow

The top-level pages of TreeFlow (listed in the left-hand navigation bar) are as follows:

Basin Data Access
Links to the basin homepages, which provide easy map-based access to reconstruction data for each of the major hydrologic basins in the western US, as well as other informational resources specific to each basin.

Background Information
What are tree-ring reconstructions? How are they developed? How can they be used? Here are informational resources which provide increasing levels of detail in answering these questions.

Applications
Describes how water managers can use, and are using, tree-ring reconstructions, with summaries of specific applications from several basins.

Workshops
Reports and presentations from the workshops on tree-ring reconstructions convened by Connie Woodhouse and Jeff Lukas around the western US since 2006.

Colorado River Streamflow: A Paleo Perspective
Multi-page feature describing the development of tree-ring reconstructions of streamflow for the Colorado River and the broader perspective they provide.

Analysis Toolbox
The “toolbox” contains two Java applets which allow different comparisons of the reconstructions (for any gage chosen by the user) with the observed flow record.

Other Resources
Provides references and web links to information resources on tree-ring reconstructions, and related topics (climate variability and change, hydrology) for the western US.

The TreeFlow Team and Support

The TreeFlow Team:

Connie Woodhouse, University of Arizona & Climate Assessment for the Southwest (formerly with NOAA Paleoclimatology Branch)
Jeff Lukas, Western Water Assessment, University of Colorado
Dan Griffin, University of Arizona & Climate Assessment for the Southwest
Katie Hirschboeck, University of Arizona & Climate Assessment for the Southwest
Holly Hartmann, University of Arizona
Ellen Lay, University of Arizona

Collaborators:

Jeremy Littell, University of Washington & Climate Impacts Group
David Meko, University of Arizona
Steve Gray, University of Wyoming & Wyoming State Climatologist

Support:

The TreeFlow team is grateful for funding or other support from the following entities:

NOAA Climate Program Office (Regional Integrated Sciences and Assessments Program)
Western Water Assessment (WWA)
Climate Assessment for the Southwest (CLIMAS)
And the many water resource managers, consultants, and others who have provided valuable feedback, and information on applications, and without whom this effort would not have been possible

A Brief History of TreeFlow

The great potential of tree rings to provide information about past climate and hydrology in the western US was first recognized in the early 1900s, but not until the advent of computers and new statistical techniques in the 1960s and 1970s, were the first “modern” reconstructions of annual streamflow developed. From 1975 to 2000, a number of streamflow reconstructions were developed for the Colorado River basin and major rivers in California, but reconstructions were not widely used in water planning and management.

The persistent drought conditions that emerged across the West in 1999, especially the extreme drought year of 2002, indicated that the observed records of streamflow in the region did not capture the full range of natural hydrologic variability. This drought, along with increasing demands on water supplies led to a need to assess the range of drought conditions that were likely to occur. Tree-ring reconstructions of streamflow, extending several hundred years or longer, provide a more complete representation of past variability. Accordingly, streamflow reconstructions attracted more interest within the water management community as a potentially useful tool for planning.

Starting in 2002, a new research and outreach project met this growing interest in tree-ring data. With a multi-year NOAA grant, Connie Woodhouse (then at NOAA), Robert S. Webb (NOAA), and Jeff Lukas (U. of Colorado) partnered with water managers in Colorado to develop over 20 streamflow reconstructions, which were made accessible through the original TreeFlow website hosted at the NOAA National Climatic Data Center's Paleoclimatology Branch. A concurrent research effort by Connie with Stephen Gray (USGS, now Wyoming State Climatologist) and David Meko (U. of Arizona) generated 10 new reconstructions for the Upper Colorado River Basin, published in 2006. In addition, a California TreeFlow website was developed with the encouragement of the California Department of Water Resources.

In 2006, with funding from Western Water Assessment, Connie and Jeff began presenting one-day technical workshops to water managers and other river stakeholders across the West, describing the new reconstructions and their use in planning. The next year, a revised TreeFlow web resource made its debut at Western Water Assessment. At the same time, David Meko and Katie Hirschboeck (U. of Arizona and Climate Assessment for the Southwest) were working with the Salt River Project to develop reconstructions for the Lower Colorado River Basin. Steve Gray and his colleagues at the University of Wyoming were generating more reconstructions for river basins in Wyoming. Water managers in other basins, such as the Pacific Northwest, expressed interesting in having this type of resource for their area as well, which led to new work in the Pacific Northwest by Jeremy Littell at the University of Washington's Climate Impacts Group.

It became clear that an expansion of the TreeFlow web resource to allow it to grow and cover the western US was needed, providing basin-centered access to the reconstructions and information about their use. A NOAA Climate Program Office grant in 2008 to Connie and the TreeFlow Team funded the development of the new, comprehensive, TreeFlow website, combining the efforts from researchers associated with Western Water Assessment, Climate Assessment for the Southwest, and the Climate Impacts Group. With the expansion comes the idea that other researchers will take ownership of the TreeFlow pages for the basins across the US in which they work, so that the pages both reflect and support partnerships with water professionals who use the data. Thus, the latest TreeFlow web resource is a designed to be a dynamic resource.

Drought, Tree-Rings, and Water Resource Management:
Assessing the Scientific Outreach of the Western Water Assessment

In 2008, Jennifer Rice of the University of Arizona, assisted by Connie Woodhouse, Jeff Lukas, and Brad Udall, conducted a study evaluating the outcomes of scientific outreach efforts of the Western Water Assessment's TreeFlow project. This study had two related parts: (1) an evaluation, based on interviews, of the outcomes of collaborative research with several water managers, consultants, and utility directors in Colorado, and (2) an evaluation, based on a web survey, of outcomes of the technical workshops for water managers and stakeholders. The study focused on how water practictioners are actually using tree-ring data in their day-to-day operations, hydrologic models of water supply, resource planning and decision-making, and the challenges they have encountered in using the data, as well as the effectiveness of the workshops in conveying information that is used by the participants.

Final report to the Western Water Assesssment and Appendices:

Final Report (PDF)

Appendix A - Information Sheet (PDF)

Appendix B - Interview Questions (PDF)

Appendix C - Web Survey Questions (PDF)

Presentation on project at 2009 meeting of American Association of Geographers (AAG):

J. L. Rice and C. A. Woodhouse, "Climate Science and Decision-Making:
The Case of Water Managers and Tree-Ring Data in the Western United States." (PDF)

Paper on project published in the Journal of the American Water Resources Association (JAWRA):

Rice, J., Woodhouse, C., and Lukas, J. (2009). Science and decision-making: Water management and tree-ring data in the western United States. Journal of the American Water Resources Association 45(5): 1248-1259. (Read Abstract)