Availability, volatility, stability, and teleconnectivity changes in prairie water supply from Canadian Rocky Mountain sources over the last millennium

• Published in: Water resources research 2013-01, Vol.49 (1), p.64-74
• Main Authors: Fleming, Sean W., Sauchyn, David J.
• Format: Article
• Language: English
• Subjects: Agricultural land; applied statistical analysis; Canadian Prairies; dendrochronology; Design engineering; Drought; Hydrology; Mountains; Paleohydrology; River basins; Rivers; Statistical methods; Volatility; Water allocation; Water availability; Water conveyance; Water management; water resource management; Water shortages; Water supply; Water use
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2012WR012831

Key Points We explore generational changes in water supply dynamics over a millennium Paleohydrologic data and statistical methods are used for the Canadian Prairies Human experiential timeframes and gauge records can be misleading Multidecadal variability can have profound implications for long‐term viability of existing water management practices and design of water conveyance, storage, and treatment infrastructure. However, baseline hydrology for water supply planning and engineering design rarely includes the full range of variability and extremes captured by proxies and models of pre‐ and postinstrumental climate and hydrology. This paper examines the paleohydrology of the Saskatchewan River Basin (SRB), where Canada's fastest growing economy and population are vulnerable to drought and heavily reliant on runoff from the Rocky Mountains. We take a novel approach to time‐series analysis of tree‐ring reconstructions of the North and South Saskatchewan Rivers. This study evaluates shifts in water availability, volatility as defined in terms of statistical dispersion, and stability as defined in terms of Shannon entropy, between adjacent 30 year windows—corresponding to the standard climatic normal period, and human generational timescales. Broadly speaking, outcomes reveal that gauge records appear unreliable as a basis for long‐term water supply planning and engineering design. For example, (1) two preinstrumental periods of stable water deficits represent sustained droughts that current water use and management could not endure, (2) hydroclimatic relationships between the two subbasins, and with the Pacific Decadal Oscillation, change over the generations, and (3) the most anomalous period of the past millennium, with coinciding high levels of availability, volatility, and stability, was about 1890–1920. This happens precisely when the SRB was transformed from prairie and parkland to agricultural land cover—and the precedents for water allocation and use were established.