HIGH RESOLUTION REACTIVE TRANSPORT: A COUPLED PARALLEL HYDROGEOCHEMICAL MODEL

Subsurface hydrogeochemical systems are an especially complex component of the terrestrial environment and play host to a multitude of interactions. Parameterizations of these interactions are perhaps the least understood component of terrestrial systems, presenting uncertainties in the predictive understanding of biogeochemical cycling and transport. Thorough knowledge of biogeochemical transport processes is critical to the quantification of carbon/nutrient fluxes in the subsurface, and to the development of effective contaminant remediation techniques. Here we present a coupled parallel hydrogeochemical model, ParCrunchFlow, as a tool to further our understanding of the governing processes and interactions in natural hydrogeochemical systems. ParCrunchFlow is a coupling of the reactive transport simulator CrunchFlow with the hydrologic model ParFlow. CrunchFlow is a multicomponent reactive flow and transport code that can be used to simulate a range of important processes and environments, including reactive contaminant transport, chemical weathering, carbon sequestration, biogeochemical cycling, and water-rock interaction. ParFlow is a parallel, three-dimensional, variably-saturated, coupled surface-subsurface flow and transport code with the ability to simulate complex topography, geology, and heterogeneity. ParCrunchflow takes advantage of the efficient parallelism built into Parflow, allowing the numerical simulation of reactive transport processes in chemically and physically heterogeneous media at high spatial resolutions. This model provides an ability to further examine the interactions and feedbacks between biogeochemical systems and complex subsurface flow fields. In addition to the details of model construction, results will be presented that show floodplain nutrient cycling and the effects of heterogeneity on small-scale mixing reactions at the Department of Energy’s Old Rifle Legacy site.