Groundwater levels and teleconnection patterns in the Canadian Prairies

Thirty one hydrological time series of shallow groundwater levels, precipitation, and moisture-sensitive tree ring chronologies were analyzed and related to two climate indices: Nino 3.4 and PDO. Spearman rank correlation and spectral analyses (multitaper method, continuous wavelet transform, and wavelet coherence) were used to document the influence of El Nino Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) on shallow (depth < 20 m) groundwater level records from the Canadian Prairies. Modes of variability in the 2-7, 7-10, and 18-22 year bands were detected and reconstructed. Correlations and wavelet coherence between these oscillation modes and the climate indices suggest that variability in the 2-7 and 7-10 year bands is highly influenced by ENSO. The oscillation modes in the 18-22 year band reflect a negative correlation with the PDO index. When either of these teleconnections (ENSO/PDO) is in their respective positive phases, groundwater levels reflect the effect of associated warmer and drier winters experienced over much of interior Canada and the US, affecting important resource inputs to the hydrological cycle and groundwater recharge.