Contribution of standardized indexes to understand groundwater level fluctuations in response to meteorological conditions in cold and humid climates

Understanding the fluctuations in groundwater levels in response to meteorological conditions is challenging, especially given the slow transit time associated with groundwater reservoirs and the short duration of time series for groundwater levels. Nevertheless, this knowledge is crucial for water resource management, especially given that global warming will drastically impact the hydrological dynamics in cold and humid climates. The objective of this work was to quantify how standardized indexes contribute to understanding groundwater level fluctuations in response to meteorological conditions in cold and humid climates and with short time series (10 to 23 years). The relationships between the standardized precipitation index (SPI), standardized temperature index (STI), global climate indexes, and standardized groundwater index (SGI) were analyzed. The reactivity of groundwater levels was examined between 2000 and 2022 using groundwater level measurements from 152 wells located between 46 ◦N and 52 ◦N in the province of Quebec (Canada). The results showed that the available time series were sufficient to provide new insights into the role of precipitation and temperature on groundwater fluctuations, demonstrating the usefulness of the indexes. One of the main contributions of this study was that hydrogeological systems in cold and humid climates go through an annual reset due to the prolonged freezing period. This annual reset was one of the drivers isolating year-to-year hydrogeological conditions, contributing to short-duration droughts.