PROJECT TITLE: High-resolution Modeling of Hydrologic Exchange Flows in the Columbia River Subbasin at the Hanford Reach
SPONSOR: U.S. Department of Energy (DOE), Office of Biological and Environmental Research (BER), as part of BER’s Subsurface Biogeochemistry Research Program (SBR). This contribution originates from the SBR Scientific Focus Area (SFA) at the Pacific Northwest National Laboratory (PNNL)
PROJECT DURATION: 1 May 2019 to present
PRINCIPAL INVESTIGATORS: Raymond Lee (PNNL)
COLLABORATORS: Pin Shuai (PNNL); David Moulton (LANL); Daniil Svyatsky (LANL); Ethan Coon (ORNL); Scott Painter (ORNL); Ahmad Jan (ORNL); Zhufeng Fang (ORNL); Zexuan Xu (LBNL)
PROJECT SUMMARY: Rivers interface with subsurface pools (e.g., banks and aquifers) that store water and retain heat and nutrients (e.g., nitrate), increasing both transit time of riverine water/nutrients and potential for biogeochemical reactions. These hydrologic exchange flows (HEFs) across river and subsurface interfaces are modulated by natural (e.g., seasonal snowmelt) and anthropogenic (e.g., hourly dam operations) factors that cause fluctuations—at different amplitudes and frequencies—in river stage and hydraulic pressure gradients. We build on recent modeling work on HEFs in the highly-managed Columbia River (at the Hanford Reach) in the Pacific Northwest, USA. We generate a 3-D unstructured mesh that has higher grid refinement along the stream network, improving mechanistic representation of dynamic hydrobiogeochemical processes, and coarser refinement elsewhere, improving computational efficiency across a larger model domain (subbasin scale). We use this mesh with the Advanced Terrestrial Simulator (ATS), an integrated surface and subsurface flow and reactive transport model that is seamlessly integrated into a high-performance computing environment (i.e., supercomputing clusters), further improving computational capability. We simulate HEF processes that control movement and storage of water, energy, and matter with more accuracy than models (e.g., PFLOTRAN) that were developed previously for the study site and that incorporated only a structured mesh across a smaller domain. Comparisons are made to better understand both physical processes and numerical model function. To support this work, we document and share publicly (in version control repositories for model code) our modeling workflow and source code in a new tradition of open science in order to make complex numerical models more accessible and reproducible to a broad community of interested scientists and stake holders.
PUBLICATIONS:
Chen, X., R. M. Lee, D. Dwivedi, K. Son, Y. Fang, X. Zhang, E. Graham, J. Stegen, J. B. Fisher, D. Moulton, and T. Scheibe. (2020) Integrating field observations and reactive transport modeling to predict watershed water quality under environmental perturbations. Journal of Hydrology, 602: 125762, doi: 10.1016/j.jhydrol.2020.125762. [link] [pdf]
Lee, R. M., D. Moulton, and E. Coon. Complete pipeline of open-access and reproducible workflows to run a high-performance computer model of surface hydrology. In prep.
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