Changes in the hydrological regime in the Upper Bow and Upper Athabasca Watersheds during the 20th century

This thesis examines 20th century regime changes for the headwaters of the Bow (1911-2005) and Athabasca (1971-2005) Rivers. Changes in precipitation and temperature associated with the Pacific Decadal Oscillation dominate the Bow streamflow record. Higher snowfall, lower mean temperatures, and greater annual discharges occur during the “cool” PDO phase (1947-1976) with lower snowfall, higher mean temperatures, and lower annual discharges during the “warm” (1925-1946, 1977-2005) phases. Any long-term linear trends in the Bow record are masked by these multidecadal trends. The Athabasca record is too short to compare to the PDO but available data show patterns similar to the Bow. Differences in percentage glacier cover result in differences in median flow dates ranging from (June 29) on the Miette (0.2% glacier cover) to July 28 on the proglacial Sunwapta River (61% glacier cover). Additionally a visualization technique is developed which provides a complementary approach to evaluating low frequency regime changes