Sauchyn Vanstone Perez-Valdivia-2011-Modes and forcing of hydroclimatic variability in the upper North Saskatchewan River Basin since 1063

In this paper the mean water year (October through September) flow of the North
Saskatchewan River (NSR) at Edmonton, Alberta is reconstructed back to 1063 A.D. using a new
network of moisture-sensitive tree-ring chronologies from limber pine and Douglas fir at seven sites in
the headwater sub-basins of the North Saskatchewan River Basin (NSRB). Over the full extent of the
proxy hydrometric record (10632007), we examined 1) the duration and severity of low flow, 2) the
dominant frequencies of periodic variability and 3) the correlation between these significant
periodicities in proxy streamflow and climate indices, specifically sea surface temperature oscillations,
which are known drivers of regional hydroclimatic variability. This new record of the paleohydrology
of the NSRB is compared to previous tree-ring reconstructions of the annul flow of the North and
South Saskatchewan Rivers. Extending the reference hydrology for the basin from decades to centuries
changes perceptions of the reliability of the water supply and understanding of the hydroclimatic
variability. The gauge record not does represent the full extent of interannual to multidecadal
variability in the tree-ring data; there are periods of low flow in the pre-instrumental record that are
longer and more severe than those recorded by the gauge.