Improving the representation of subsurface water movement in land models

One reason for selecting land models over simpler models is that their physically-based backbone enables wider application under different conditions. This study evaluates the temporal variability in streamflow simulations in land models.

Specifically, we evaluate how the subsurface structure and model parameters control the partitioning of water into different flow paths and the temporal variability in streamflow. Moreover, we use a suite of model diagnostics, typically not used in the land modeling community to clarify model weaknesses and identify a path toward model improvement. Our analyses show that the typical land model structure, and their functions for moisture movement between soil layers (an approximation of Richards equation), has a distinctive signature where flashy runoff is superimposed on slow recessions.