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Abstract

Geochemical models are used to seek answers about composition and evolution of groundwater, spill remediation, viability of geothermal resources and other important geoscientific applications. To understand these processes, it is useful to evaluate geochemical model response to different input parameter combinations. Running the model with varying input parameters creates a large amount of output data. It is a challenge to screen this data from the model to identify the significant relationships between input parameters and output variables. For addressing this problem we developed a Visual Analytics approach in an ongoing collaboration between Geoinformatics and Hydrogeology sections of GFZ German Research Centre for Geosciences. We implement our approach as an interactive data exploration tool called the GCex. GCex is a Visual Analytics approach and prototype that supports interactive exploration of geochemical models. It encodes many-to-many input/output relationships by the simple yet effective approach called Stacked Parameter Relation (SPR). GCex assists in the setup of simulations, model runs, data collection and result exploration, greatly enhancing the user experience in tasks such uncertainty and sensitivity analysis, inverse modeling and risk assessment. While in principle model-agnostic, the prototype currently supports and is tied to the popular geochemical code PHREEQC. Modification to support other models would not be complicated. GCex prototype was originally written by Janis Jatnieks at GFZ-Potsdam. It relies on Rphree (R-PHREEQC geochemical simulation model interface) written by Marco De Lucia at GFZ-Potsdam. A compatible version of Rphee is bundled with this installation.