Development of a simple groundwater model for use in climate models and evaluation with Gravity Recovery and Climate Experiment data

Groundwater interacts with soil moisture through the exchanges of water between the unsaturated soil and its underlying aquifer under gravity and capillary forces. Despite its importance, groundwater is not explicitly represented in climate models. This paper developed a simple groundwater model (SIMGM) by representing recharge and discharge processes of the water storage in an unconfined aquifer, which is added as a single integration element below the soil of a land surface model. We evaluated the model against the Gravity Recovery and Climate Experiment (GRACE) terrestrial water storage change (Δ S ) data. The modeled total water storage (including unsaturated soil water and groundwater) change agrees…