Groundwater and land surface models were combined to improve water and energy cycle simulations. The new model, GWSiB, integrates a land surface model (SiB2) with a groundwater model (AquiferFlow) to better represent subsurface water processes and lateral groundwater flow. By using soil moisture data from the groundwater model, the coupled model simulates infiltration, evapotranspiration, and energy transfer more accurately. The researchers tested the model's sensitivity to groundwater depth and hydraulic conductivity, validated it with field measurements, and applied it to the Heihe River basin in China. The coupled model showed improved regional simulation capabilities for water and energy cycles.