HR: 17:20h
AN: GC52B-06    [PDF]
TI: Hydroclimatic Variability in the Northern Interior of North America
AU: * Sauchyn, D J
EM: sauchyn@uregina.ca
AF: Prairie Adaptation Research Collaborative, University of Regina 150 - 10 Research Drive, Regina, SK S4S 7J7 Canada
AU: Beriault, A L
EM: sauchyn@uregina.ca
AF: Prairie Adaptation Research Collaborative, University of Regina 150 - 10 Research Drive, Regina, SK S4S 7J7 Canada
AU: Stroich, J N
EM: stroichj@uregina.ca
AF: Prairie Adaptation Research Collaborative, University of Regina 150 - 10 Research Drive, Regina, SK S4S 7J7 Canada
AU: Yu, G
EM: uyuge200@uregina.ca
AF: Prairie Adaptation Research Collaborative, University of Regina 150 - 10 Research Drive, Regina, SK S4S 7J7 Canada
AB: The least annual precipitation in the western interior of North America occurs in the northern Great Plains. A subhumid climate extends to high-latitudes in the rainshadow of the western cordillera. We have established a network of 42 moisture-sensitive tree-ring chronologies extending from the plains of Montana, Alberta and Saskatchewan to the boreal shield of the Northwest Territories (NWT). A network of this geographic extent enables the analysis of annual to decadal hydroclimatic variability at a range of spatial scales. The hydroclimatic signal is relatively coherent along a north-south gradient; paleo drought is evident at relatively high latitudes in the western NWT. There is less consistency from west to east. The variability over time is marked at many sites by a mid-19 century shift from the dominance of decadal variance (sustained wet and dry conditions) to more interannual variance that characterized the 20th century and thus the instrumental hydroclimatic record. Because stream flow integrates precipitation of over months and watersheds, it is generally more highly correlated with residual tree-ring width than precipitation data. Residual tree-ring width accounts for 30-60% of the variance in seasonal and annual precipitation and streamflow. The unexplained variance reflects the tendency for tree-ring widths to underestimate unusually wet conditions, because soil properties and tree physiology limit the response of tree growth to precipitation. Our interest, however, is primarily in dry conditions and low flows. Tree-rings are a particularly good proxy of the timing and duration of drought. This research addresses concerns about the socio-economic and environmental impacts of drought in this region and about water supply forecasting based on relatively short instrumental records. From tree rings, we are able to extend hydrometric records beyond the several decades of instrumental data, although the short length of gauge records presents a challenge for calibrating and validating the tree-ring based reconstructions. The application of our proxy hydroclimate records to drought and water supply planning requires that the data be delivered and used in the context of risk assessment. Therefore, we have taken a Monte Carlo approach to expressing uncertainty in the tree ring reconstruction and to estimating probability of drought, annual and seasonal precipitation and streamflow below specific thresholds.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1800 HYDROLOGY
DE: 3344 Paleoclimatology
SC: Global Climate Change [GC]
MN: 2003 Fall Meeting