Connections between groundwater depth, surface runoff and plant water use are well established. Still, groundwater surface water interactions are largely excluded or greatly simplified in continental and global modeling efforts. This is an identified research gap, as increasingly studies are finding that groundwater representations are needed to correctly capture low frequency variability and extreme events in large models. High-resolution physically based groundwater surface water simulations are now feasible at the national scale due to computational and modeling advances. These tools have facilitated novel quantifications of groundwater surface water interactions and the contribution of lateral groundwater flow to watershed systems. Still, significant challenges remain in the application and transparency of these large and computationally intensive tools at global scales. Here I will present work to develop an integrated hydrologic modeling platform of the US, including scientific findings with the model so far and scientific needs to advance these tools further.
