| Summary: | The impacts of climate variability and change on streamflow are of increasing concern, particularly as human demands on water supplies compete with the needs of natural ecosystems. The consequences on the hydrological cycle are predicted to be most severe for mid- to high-latitude regions. Of particular concern is reduced mountain snow accumulation and related reductions in the snow- and glacier-derived water supply. In northern British Columbia (BC), recent snowpack declines have caused a unique water management challenge. Diminishing water security in a region considered water-abundant has intensified over the last decade. Characterizing the climate controls on hydrologic variability is a priority for developing baseline information required for water supply forecasting. This research focuses on developing multi-century, annually-resolved records of snow water equivalent (SWE) and streamflow to provide a better understanding of long-term hydroclimate variability for the design and implementation of management strategies that balance riverine ecosystem services, such as recreation and fish habitat, with increasing economic and social demands. Climate sensitive tree-ring chronologies provide the opportunity to extend instrumental records of hydroclimate by capitalizing on the influence of climate on both annual radial growth and seasonal runoff. Traditional dendrohydrology relies on moisture-limited tree species from dry, continental settings. This dissertation presents a new method by focusing on mid- to high-elevation conifers sensitive to snowpack variability. Ring-width and maximum latewood density records from mountain hemlock (Tsuga mertensiana (Bong.) Carriere), white spruce (P. glauca (Moench) Voss), and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) stands were collected at sites in northern BC. Dendrochronological techniques were used to develop a: 1) 223-year record of April 1 SWE for the Stikine River basin; 2) 417-, 716-, and 343-year record of summer streamflow for the Skeena, Nass and Stikine ...
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