Teleconnections and interannual variability in Canadian groundwater levels

Relatively little is known about the impact of climate change on groundwater. The analysis of large-scale climatic patterns such as the well-known El Niño Southern Oscillation Index could provide a better comprehension of the causes of recharge variations in aquifers and therefore improve the knowledge related to processes behind the variability of groundwater level time series. This topic has been studied to a limited extent in other parts of the world, but no study has yet used this approach across Canada. In this work, correlation and wavelet analyses and wavelet coherence are used to gain a broader understanding of the interannual dynamics of recharge through the use of groundwater level records in three Canadian regions, namely Prince Edward Island (PEI), southern Manitoba in the vicinity of Winnipeg (MB) and Vancouver Island (VI). Cause and effect linkages between four climatic indices (the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), the Pacific-North American pattern (PNA) and the El Niño Southern Oscillation represented by the Multivariate ENSO Index (MEI)), groundwater level time series, as well as precipitation and temperature time series are investigated. The length of the available historical records of groundwater levels at the three sites is 32 years (1974–2005). The three Canadian regions studied show drastically different patterns of variability evolution for the hydrogeological records. Groundwater level variability on PEI is mostly influenced by the NAO and the AO. The variability of groundwater levels in the MB region is partly explained by PNA. In the VI region, NAO, AO and MEI appear to impact the pattern of groundwater variability.