An integrated model of surface and subsurface flows

In this paper, we present a coupled hydrological model to simulate all major flow pathways at the watershed scale. The modeling domain includes three layers identified as: (i) the overland flow zone; (ii) the unsaturated groundwater zone; and (iii) the saturated groundwater zone. In this approach, a two-dimensional overland flow model is coupled with a one-dimensional unsaturated groundwater zone model and a two-dimensional vertically averaged saturated groundwater zone model. The ground surface and the groundwater table are used as the two limiting boundaries of the unsaturated zone model and infiltration and/or constant head conditions are used as the internal boundary condition linking the three zones. The proposed model is limited to lowland areas with negligible horizontal fluxes in the unsaturated zone. This approach requires less computational resources when compared to three-dimensional analogue.