(Water Management, Conservation of Natural Resources)
Water resource management requires knowledge of the natural variability in streamﬂow
over multiple time scales. Reconstructions of streamﬂow derived from moisture-sensitive trees extend, in both time and magnitude, the variability provided by relatively short gage records. In this study, we present a network of 14 annual streamﬂow reconstructions, 300–600 years long, for gages in the Upper Colorado and South Platte River basins in Colorado generated from new and existing tree-ring chronologies. Gages for the reconstruction were selected on the basis of their importance to two of the largest Colorado Front Range water providers, who provided the natural ﬂow data for the calibration with tree-ring data. The reconstruction models explain 63–76% of the variance in the gage records and capture low ﬂows particularly well. Analyses of the reconstructions indicate that the 20th century gage record does not fully represent the range of streamﬂow characteristics seen in the prior two to ﬁve centuries. Multi-year drought events more severe than the 1950s drought have occurred, notably in the 19th century, and the distribution of extreme low ﬂow years is markedly uneven over the past three centuries. When the 14 reconstructions are grouped into Upper Colorado, northern South Platte, and southern South Platte regional ﬂow reconstructions, the three time series show a high degree of coherence, but also time-varying divergences that may reﬂect the differential inﬂuence of climatic features operating in the western U.S. These reconstructions are currently being used by water managers to assess the reliability of water supply systems under a broader range of conditions than indicated by the gauge records alone.
Woodhouse, C. & Lukas, J. (2006).
Climatic Change, 78:2-4, 293-315. doi: 10.1007/s10584-006-9055-0