Developing a predictive understanding of the terrestrial water cycle at local to global scale is essential for accurate assessment of water resources, agricultural production, and energy generation given current climate variability. Higher spatial resolution in the land component of the Energy Exascale Earth System Model (E3SM) project alone is insufficient to meet the U.S. Department of Energy’s 10-year vision for the Earth System Modeling program. Next generation hyperresolution terrestrial models need to not only move beyond one-dimensional systems by including scale appropriate 2D and 3D physics formulations, but also use numerical discretization schemes that are appropriate for terrain-following, non-orthogonal 3D grids.

In this project, we are developing a standalone, scalable numerical library, named TDycore, which solves the three-dimensional transport of water in the subsurface for non-orthogonal grids. The TDycore library is being built on top of the Portable, Extensible Toolkit for Scientific Computation (PETSc) library. The TDycore library will support the following two spatial discretization schemes that support non-orthogonal grids: (i) mixed finite element, and (ii) multi point flux approximation. The temporal discretization is provided by via PETSc’s time stepping methods. The TDycore library will be coupled the E3SM Land Model (ELM) to resolve 3D subsurface flow. We will present results for a range of problems that demonstrate verification of the TDycore library and the application of the ELM-TDycore model at watershed scales. The enhanced modeling capabilities provided by the TDycore library will lead to a more mechanistic representation of hydrological cycle in the E3SM.