Groundwater reservoir management scenarios in Yorkton area, Canada: effects of climate changes and the dynamic interchange with surface water

Abstract

Management of water resources has gained significant attention over the last decade to cope up with climate change as well as with the growing industrial and agricultural demands. Therefore, integrated approaches are now being used widely for ensuring sustainable usage of water resources. It is apparent that, in many cases, groundwater and surface water systems are not isolated and continuous interchange between them always exists. Different climatic patterns influence the seepage of groundwater systems to/from surface water bodies. During rainy seasons, groundwater is likely to seep towards surface water systems and vice versa during drought periods. Therefore, any correct understanding of the behavior of a regional aquifer system should incorporate surface water bodies that exist in the simulation domain and quantify the exchange rates between them.

The scope of this study focuses on the management scenarios of one of the groundwater reservoirs in the Yorkton area in Saskatchewan, Canada. A surface–subsurface water flow model for the Leech Aquifer, has been established to evaluate the potential impacts of climate change and abstraction rates on the groundwater resources. HydroGeoSphere, a fully coupled and a spatially distributed hydrological GW-SW model is exercised here for its capability to account for both groundwater and surface water interactions. The primary purpose of this conducted study is to assure a certain level of sustainability for any kind of future management of this specific aquifer under possible climate change settings. Estimation of exchange fluxes across the groundwater-surface water interface and groundwater recharge fluxes have been executed throughout this modeling study to fix up a sustainable withdrawal rate.

The developed model has been calibrated and validated using observations of hydraulic heads of four monitoring wells for the period from 2002 to 2015. From the analysis, it could be stated that the calibration process to identify the appropriate value of the hydraulic conductivities for both aquifer and aquitard formations based on local geological strata is the major challenge in this regard. Simulation results of groundwater heads displayed very good agreement with the observed data. However, the performance of this developed model has been assessed by computing errors using some widely used statistical measurement tools (e.g. RMSE, NSE, P-bias and MAE) for such kind of modeling case studies. This study explores the magnitude, temporal variability and spatial distribution of exchange fluxes between the aquifer and its interconnected lakes. Simulation results provide evidence of substantial exchange fluxes and their vital role in water balance and groundwater recharge over the modeling catchment. In addition, multiple scenarios and their interpretations have been analyzed to ensure proper management of this aquifer system. For instance, outcomes of one of the scenarios revealed the dominance of precipitation as a recharge flux in comparison to snowmelt for this modeling region.

In general, this study has been conducted to verify the capability of a fully integrated numerical model in reproducing observed GW–SW exchange processes in a complex aquifer system. These model-based approximations can serve as a prediction guide in determining other ecologically relevant fluxes at the GW-SW interface to ensure water quality and hence for further water resources management.

Keywords: Sustainable usage, Integrated management, Interactions, Fully coupled, Exchange Fluxes.

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