The Impact of Ice Sheet Geometry on Meltwater Ingress and Reactive Solute Transport in Sedimentary Basins

We investigate the effect of ice sheet geometry on groundwater flow patterns and meltwater ingress in a hypothetical sedimentary basin. The simulation results indicate that meltwater ingress is much greater in 3D domains with a relatively narrow ice sheet extent compared to a wide ice sheet, or a simplified 2D model. In high permeability units (HPUs), the simulated meltwater penetration depth can reach up to 750 m in 3D domains compared to 400 m in a comparable 2D domain. In low permeability units (LPUs), very limited meltwater penetration occurs, indicating that ice sheet geometry and model dimensionality do not substantially affect water flow in these units. A conservative tracer, with a source located at a depth of 500 m in both HPUs and LPUs, illustrates that solutes can be transported to greater depths in HPUs for a narrow ice lobe scenario, in comparison to a wide ice sheet or the 2D approach. Tracer transport in LPUs is unaffected by ice sheet geometry. Similarly, simulation results indicate that the ingress of dissolved oxygen (O2) into HPUs is most substantial below a narrow ice lobe, while O2 ingress into LPUs is not affected by ice sheet geometry. The numerical experiments indicate that 3D analysis will give more comprehensive results for flow patterns and reactive solute transport subjected to glaciation/deglaciation cycles in the case of a narrow ice lobe, but also suggest that a 2D approach might provide an adequate representation for the case of a relatively wide ice sheet. Plain Language Summary Glaciation events are natural phenomena related to large‐scale climate fluctuations. Groundwater systems can be significantly changed when ice sheets advance and retreat over the land surface. The ice sheet not only may produce meltwater, but also compresses the rocks and changes rock properties. The outer margins of the ice sheet can be narrow or wide relative to the lateral extent of the underlying rock units. Computer simulations based on mathematical equations provide an efficient method to analyze how the ice sheet shape affects groundwater flow patterns. These simulations are complex, requiring substantial computational resources, and previous studies usually have simplified the three‐dimensional real‐world problem by using a two‐dimensional approximation. This research evaluates the adequacy of this simplified approach, revealing that the two‐dimensional approach may misrepresent groundwater flow patterns and solute transport in the subsurfac