DOI: 10.25921/89qb-b134
title: NOAA/WDS Paleoclimatology - Meko et al. 2001 Sacramento River Annual Flow Reconstruction

description: A time series of annual flow of the Sacramento River, California, is reconstructed to A.D. 869 from tree rings for a long-term perspective on hydrologic drought. Reconstructions derived by principal components regression of flow on time-varying subsets of tree-ring chronologies account for 64 to 81 percent of the flow variance in the 1906 to 1977 calibration period. A Monte Carlo analysis of reconstructed n-year running means indicates that the gaged record contains examples of drought extremes for averaging periods of perhaps = 6 to 10 years, but not for longer and shorter averaging periods. For example, the estimated probability approaches 1.0 that the flow in A.D. 1580 was lower than the lowest single-year gaged flow. The tree-ring record also suggests that persistently high or low flows over 50-year periods characterize some parts of the long-term flow history. The results should contribute to sensible water resources planning for the Sacramento Basin and to the methodology of incorporating tree-ring data in the assessment of the probability of hydrologic drought.
description: Meko et al. 2001 Sacramento River Annual Flow Reconstruction. Reconstruction of total annual flow, in millions of acre/feet, of the Sacramento River, based on tree ring chronologies. Note: Two reconstructions of Sacramento River annual streamflow by David Meko and colleagues are archived at the World Data Center for Paleoclimatology. Because they are very similar and were published in the same year (2001), this text clarifies the relationship between the two reconstructions. In the late 1990s, Meko and colleagues generated a new reconstruction of streamflow for the Sacramento River, extending from AD 869 to 1977 (this file). The reconstruction was based on a set of 36 tree-ring chronologies collected in California, Oregon, and Nevada by numerous investigators from the late 1970s to the mid-1990s. This reconstruction was published in 2001 in the Journal of the American Water Resources Association (JAWRA). Because the early portion of the "JAWRA" reconstruction depended heavily on chronologies outside of the Sacramento River basin, Meko generated a second, updated reconstruction of Sacramento River flow (and also of its tributary, the Feather River) in 1999-2001.  This reconstruction was based on a set of 42 tree-ring chronologies, 11 of which were not used in the previous reconstruction, including three collected specifically for the new work. The updated reconstruction extends from AD 901 to 1977 and was published in a report to the California Department of Water Resources (CDWR) issued in July 2001.  The newer CDWR reconstruction is archived with the WDC Paleo at: https://www.ncei.noaa.gov/pub/data/paleo/treering/reconstructions/california/sacramento-flow-cdwr.txtBoth reconstructions use three time-varying subsets of the tree-ring data to take advantage of all of the data available in each time period, and explain a very similar fraction (~80%) of the variance in the gaged record. The updated reconstruction is probably more robust because of the expanded spatial coverage of the tree-ring dataset, particularly early in the reconstruction period.