Diffuse loading of surface water from groundwater in areas with shallow groundwater tables: Quasi-2-D vs. 2-D simulation

The discharge of water and solutes from groundwater to surface water can be simulated using a quasi two-dimensional (2-D) approach. In this approach, variably saturated flow is simulated in a vertical 1-D column and the discharge to the surface water system is simulated using conceptual relations. To test the quasi-2-D approach of SWAP/ANIMO, the results are compared to the results from a 2-D, variably-saturated flow and transport model: Hydrus-2D. The results show that in the case of stationary flow and/or conservative transport the results of the quasi-2-D approach are comparable to those of Hydrus-2-D. For variable flow conditions and reactive transport, the results of the two models differ considerably.