Application of Streamflow Reconstruction to Water Resources Management

Abstract

Streamflow reconstruction—the statistical augmentation of streamflow time series using tree-ring data—has been increasingly applied as a planning and research tool in water resources studies over the past few decades. Streamflow reconstruction in North America has evolved from a largely qualitative science in the first half of the twentieth century into a highly quantitative science that draws heavily on probabilistic theory. The historical development of streamflow reconstruction from a western United States perspective is reviewed, with an emphasis on developments of the last 30 years. Contributions to the study of water resources are discussed. Temporal extension of gauge flow records is the central contribution of the paleo record, but the statistical summary of those records and their manner of presentation are important factors in determining the value to water resources management. Probabilistic interpretations of flow reconstructions are needed because of uncertainty stemming both from limitations of the basic data and from the reconstruction process itself. Case studies are presented for the Colorado River, at the large spatial scale, and for the water-supply region of a metropolitan area—Denver, Colorado—at the smaller scale. Interaction of the tree-ring scientists with water managers and the public is a hallmark of modern applied reconstruction studies. Aspects receiving increased attention are the extent to which seasonal flows can be resolved, and how water managers and planners concerned with future conditions can overlay impacts of expected climate change on the natural hydroclimatic variability of the past as reflected in the tree-ring record.