BioRT-Flux-PIHM v1.0: a biogeochemical reactive transport model at the watershed scale

Journal Article · 17 January 2022 · Geoscientific Model Development (Online)

DOI: https://doi.org/10.5194/gmd-15-315-2022 · OSTI ID:1981301

Zhi, Wei  ^[1]; Shi, Yuning  ^[2]; Wen, Hang ^[2]; Saberi, Leila ^[3]; Ng, Gene-Hua Crystal ^[3]; Sadayappan, Kayalvizhi ^[2]; Kerins, Devon ^[2]; Stewart, Bryn ^[2]; Li, Li  ^[2]

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1. Pennsylvania State University, University Park, PA (United States); The Pennsylvania State University, State College, PA 16802, USA
2. Pennsylvania State University, University Park, PA (United States)
3. University of Minnesota, Twin Cities, MN (United States)

Watersheds are the fundamental Earth surface functioning units that connect the land to aquatic systems. Many watershed-scale models represent hydrological processes but not biogeochemical reactive transport processes. This has limited our capability to understand and predict solute export, water chemistry and quality, and Earth system response to changing climate and anthropogenic conditions. Here we present a recently developed BioRT-Flux-PIHM (BioRT hereafter) v1.0, a watershed-scale biogeochemical reactive transport model. The model augments the previously developed RT-Flux-PIHM that integrates land-surface interactions, surface hydrology, and abiotic geochemical reactions. It enables the simulation of (1) shallow and deep-water partitioning to represent surface runoff, shallow soil water, and deeper groundwater and of (2) biotic processes including plant uptake, soil respiration, and nutrient transformation. The reactive transport part of the code has been verified against the widely used reactive transport code CrunchTope. BioRT-Flux-PIHM v1.0 has recently been applied in multiple watersheds under diverse climate, vegetation, and geological conditions. This paper briefly introduces the governing equations and model structure with a focus on new aspects of the model. It also showcases one hydrology example that simulates shallow and deep-water interactions and two biogeochemical examples relevant to nitrate and dissolved organic carbon (DOC). These examples are illustrated in two simulation modes of complexity. One is the spatially lumped mode (i.e., two land cells connected by one river segment) that focuses on processes and average behavior of a watershed. Another is the spatially distributed mode (i.e., hundreds of cells) that includes details of topography, land cover, and soil properties. Whereas the spatially lumped mode represents averaged properties and processes and temporal variations, the spatially distributed mode can be used to understand the impacts of spatial structure and identify hot spots of biogeochemical reactions. The model can be used to mechanistically understand coupled hydrological and biogeochemical processes under gradients of climate, vegetation, geology, and land use conditions.

• Research Organization: Pennsylvania State University, University Park, PA (United States)
• Sponsoring Organization: USDOE Office of Science (SC); National Science Foundation (NSF)
• Grant/Contract Number: SC0020146
• OSTI ID: 1981301
• Journal Information: Geoscientific Model Development (Online), Journal Name: Geoscientific Model Development (Online) Journal Issue: 1 Vol. 15; ISSN 1991-9603
• Publisher: Copernicus Publications, EGUCopyright Statement
• Country of Publication: United States
• Language: English