Evaluating the sustainability of groundwater abstraction in small watersheds using time series analysis

Groundwater is crucial in meeting the water needs of communities, industries, and ecosystems. The effective management of this resource is essential for maintaining the long-term stability of both the environmental and socio-economic conditions. This work focuses on assessing the sustainability of groundwater abstraction in Charlottetown, Prince Edward Island, specifically from well fields situated within the small-scale watersheds of Winter River and North River. The advanced time series analysis techniques, including Vector Error Correction Models (VECM), Impulse Response Functions (IRFs), and Forecast Error Variance Decomposition (FEVD) are employed to investigate the relationships among precipitation, temperature, groundwater abstraction, and stream flows. The analysis of IRFs reveals dynamic responses of streams to various shocks, including the variation of temperature, precipitation and well discharges, which showcase related immediate impacts, short-term responses, and long-term relationships. Temperature fluctuations exhibit complex responses, with short-term response decreases followed by sustained increases. Precipitation emerges as a dominant factor, showing sustained positive impacts on streamflow. Well operations significantly influence stream ecosystems, emphasizing the importance of optimized well operation strategies. The FEVD revealed that the first forecast horizon for all stream flows is primarily influenced by past shocks in precipitation with 16–55% in addition to other factors. The walk forward cross-validated forecast values for the next 24 months align with seasonal trends, reflecting declining discharge in summer, variable but generally decreasing discharge in fall, and increased discharge in winter and spring. The study findings provide recommendations for sustainable groundwater abstraction practices, including optimizing well operation strategies, community and stakeholder engagement, and ecosystem preservation.