Modelling streamflow depletion under different groundwater pumping scenarios involving the Dalmeny aquifer in Saskatchewan

Abstract

In the Dalmeny Basin both ecosystems and people rely on local watercourses so it is important to determine how groundwater pumping could affect streamflow. As such, simulation of how streamflow would deplete under different scenarios was done using parameters within realistic ranges present in the area. From there the upper limit to the pumping rate before significant ecological damage would occur in the North Saskatchewan River, the region's notable watercourse, was determined. The main method was the use of the R package called streamDepletr and its built in Glower, Hunt, and Hantush functions. One notable result is that a streamed with a weighted average composition resulted in the threshold before ecological damage being lower than if it were solely composed of the Upper floral unit. Additionally, the system is most sensitive to variations in storativity. In comparing the Glover, Hunt, and Hantush methods, it was also discovered that for identical scenarios, the Glover method predicts the most stream depletion white the Hantush method predicts the least. It was determined that to surpass the significant ecological damage threshold, the pumping rate from the Dalmeny Aquifer would have to surpass its recharge rate. Practically, reaching this point is unnecessary given the area's current and historical groundwater usage, as well as unsustainable for the aquifer itself.