A 1D-3D Coupled Model for Simulating Variably Saturated Flow at Regional-scale

In order to seek a compromise scheme between fully three-dimensional model based on Richards equation and groundwater model which oversimplifies the unsaturated zone processes, a 1D-3D coupled model for simulating variably saturated flow at regional scale is proposed in this paper. Through the flux between junction nodes from 1D and 3D grid systems, the two separated systems are coupled by Darcy’s law. Some cases are simulated here to assess the performance of the proposed model. The results show that by reducing the number of nodes at the upper part of soil, this model greatly reduces the computing time compared with other fully 3D model, e.g., Feflow and Hydrus. The coupled model is easy to replenish with hydrological process model, and it can be used in simulating variably saturated flow at regional-scale.