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Modelling DOC in the Canadian Sub-Arctic

Shanta Sharma recently defended her Masters thesis on modelling dissolved organic carbon (DOC) in the Canadian sub-Arctic. This was one of the most northerly applications of the INCA family of models and brought some unique challenges and insights.

The sub-Arctic in Canada and elsewhere is likely to experience hydroclimatic regime change associated with a rapidly changing climate. Simulations of landscape-scale carbon (C) budgets and pollutant transfer are needed by northern managers and stakeholders to understand and mitigate these possible impacts. The project simulated dissolved organic carbon (DOC) fluxes in a hydrologically complex watershed (Baker Creek) in the Northwest Territories. Discharge, DOC concentration, and DOC export were simulated PERSiST and INCA-C. The models were calibrated against available (2012-2016) discharge and DOC concentration data in sub-catchments of Baker Creek. The model successfully reproduced flow (R2: 0.87–0.94; NS: 0.82–0.91) and captured some aspects of DOC concentration dynamics (R2: 0.19–0.31).

Possible future conditions were simulated using two climate scenarios (elevated temperature (T), elevated temperature and precipitation (T+P)), and compared against a baseline scenario. Average discharge is projected to decrease under scenario T (22–27% of baseline) and increase (116–175% of baseline) under the T+P scenario. In this scenario, early winter increases in discharge suggest a change in hydroclimatic regime from nival to combined nival and pluvial. Future DOC fluxes are projected to decrease (24–27% of baseline) under scenario T and increase (64–81% of baseline) in the T+P scenario, with much of the increase in DOC export occurring during early winter. Any future increase in DOC export from Baker Creek may increase the mobility of previously deposited airborne metal contaminants, e.g., arsenic from Giant Mine.

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