Modelling Subarctic watershed dissolved organic carbon response to hydroclimatic regime

Area of Science:

• Environmental science
• Hydrology
• Climate change research

Background:

• Global climate change is altering hydroclimatic regimes, affecting freshwater resources.
• Northern hemisphere high latitudes store significant terrestrial carbon, making them vulnerable to changing water patterns.
• Understanding carbon budgets and pollutant transfer is crucial for assessing climate change impacts in these regions.

Purpose of the Study:

• To model streamflow, dissolved organic carbon (DOC) concentration, and DOC export in a warming northern Canadian catchment.
• To project the effects of future climate scenarios on carbon dynamics.
• To inform strategies for monitoring and managing northern freshwater ecosystems.

Main Methods:

• Utilized a dynamic modeling approach with the Integrated Catchment model for Carbon (INCA-C).
• Calibrated the model using multi-year data (2012-2016) representing diverse hydrologic conditions.
• Simulated model runs over 30-year periods for baseline and two future climate scenarios (elevated temperature, and elevated temperature with precipitation).

Main Results:

• Predicted decreased average discharge (22-27%) under elevated temperature, but increased discharge (116-175%) under elevated temperature and precipitation.
• Projected a shift from a nival to a combined nival and pluvial hydroclimatic regime under the warmer, wetter scenario.
• Anticipated a decrease in average DOC flux (24-27%) with elevated temperature alone, but a significant increase (64-81%) under elevated temperature and precipitation due to enhanced catchment connectivity.
• Identified early winter as the period with the largest projected increase in DOC export.

Conclusions:

• Future climate scenarios, particularly warmer and wetter conditions, are predicted to significantly increase carbon export from northern catchments.
• Changes in dissolved organic carbon export suggest potential for broader ecosystem shifts.
• Increased carbon export, especially in early winter, highlights the need for enhanced monitoring in vulnerable northern regions.