Evaluating Bank-Filtration Occurrence in the Province of Quebec (Canada) with a GIS Approach

Abstract

Due to the abundance of surface water in the province of Quebec, Canada, it is suspected that many groundwater wells are pumping a mixture of groundwater and surface water via induced bank filtration (IBF). The regulatory framework in Quebec provides comprehensive guidelines for the development and monitoring of surface water and groundwater drinking water production systems. However, the regulations do not specifically address hybrid groundwater-surface water production systems such as IBF sites. More knowledge on the use of IBF in the province is needed to adjust the regulations with respect to the particularities of these systems. In order to provide a first evaluation of municipal wells potentially using IBF and the corresponding population served by these wells, a Geographic Information Science framework (GISc) was used to implement an IBF spatial database and calculate the distance from each well to the nearest surface water body. GISc is based on open source GIS programs and openly available data, to facilitate the reproducibility of the work. From this provincial scale approach, we show that nearly one million people are supplied by groundwater from municipal wells located <500 m from a surface water body, and half a million have a significant probability to be supplied by IBF wells. A more focused look at the watershed scale distribution of wells allows us to improve our interpretations by considering the aquifer type and other regional factors. This approach reveals strong spatial variability in the distribution of wells in proximity to surface water. Of the three selected regions, one has a high potential for IBF (Laurentides), one requires additional information do draw precise conclusions (Nicolet), and the third region (Vaudreuil-Soulanges) is unlikely to have widespread use of IBF. With this study, we demonstrate that extensive use of IBF is likely and that there is a need for improved understanding and management of these sites in order to properly protect the drinking water supply.

Quantifying floodwater impacts on a lake water budget via volume-dependent transient stable isotope mass balance

“…Lake A water sampling was performed in the northern part of the lake for logistical reasons and due to ease of accessibility. As horizontal homogeneity has been previously demonstrated by Pazouki et al (2016), the water samples were deemed representative of the whole waterbody.…”

“…In comparison, the neighbouring lake (i.e. lake B) does not undergo yearly recurrent flooding and was shown to be more mineralized with a Na-Cl water type, likely originating from the road salt contamination of regional groundwater (Pazouki et al, 2016). Biehler et al (2020) similarly reported hydrological controls on the geochemistry of a shallow aquifer in an hyporheic zone, where the river stage influenced the mixing ratio between river water and the deeper aquifer.…”

Managed Aquifer Recharge for Water Resilience

“…In the same area of south east Canada that contains many streams and lakes and a huge number of municipal water supply wells, Patenaude et al [6] posed the question "which of these are in fact induced river bank filtration wells that may require greater protection from potential surface water pollution?" They used a GIS with multi-criteria decision analysis (MCDA) to categorise the likelihood of wells inducing infiltration from surface water.…”

Optimizing short time-step monitoring and management strategies using environmental tracers at flood-affected bank filtration sites

“…BF systems in hilly terrains were also reported to be vulnerable to contamination during flood events (Sandhu et al, 2013). In the province of Quebec (Canada), it is not rare to observe pathogen indicators (such as total coliforms) in municipal pumping wells during springtime freshets, which is perhaps linked to the fact that bank filtration is likely performed unintentionally due to the large density of lakes and rivers, and the close proximity of municipal wells to those waterbodies (Patenaude et al, 2020).…”