Climatic Controls on Mean and Extreme Streamflow Changes Across the Permafrost Region of Canada

Climatic change is affecting streamflow regimes of the permafrost region, altering mean and extreme streamflow conditions. In this study, we analyzed historical trends in annual mean flow (Q(mean)), minimum flow (Q(min)), maximum flow (Q(max)) and Q(max) timing across 84 hydrometric stations in the permafrost region of Canada. Furthermore, we related streamflow trends with temperature and precipitation trends, and used a multiple linear regression (MLR) framework to evaluate climatic controls on streamflow components. The results revealed spatially varied trends across the region, with significantly increasing (at 10% level) Q(min) for 43% of stations as the most prominent trend, and a relatively smaller number of stations with significant Q(mean), Q(max) and Q(max) timing trends. Temperatures over both the cold and warm seasons showed significant warming for >70% of basin areas upstream of the hydrometric stations, while precipitation exhibited increases for >15% of the basins. Comparisons of the 1976 to 2005 basin-averaged climatological means of streamflow variables with precipitation and temperature revealed a positive correlation between Q(mean) and seasonal precipitation, and a negative correlation between Q(mean) and seasonal temperature. The basin-averaged streamflow, precipitation and temperature trends showed weak correlations that included a positive correlation between Q(min) and October to March precipitation trends, and negative correlations of Q(max) timing with October to March and April to September temperature trends. The MLR-based variable importance analysis revealed the dominant controls of precipitation on Q(mean) and Q(max), and temperature on Q(min). Overall, this study contributes towards an enhanced understanding of ongoing changes in streamflow regimes and their climatic controls across the Canadian permafrost region, which could be generalized for the broader pan-Arctic regions.

Automated summary

This study analyzed the historical trends in streamflow components of the permafrost region in Canada, finding spatially varied trends and significant impacts of temperature and precipitation on streamflow. The study revealed that temperature has a dominant control over minimum flow, while precipitation plays a significant role in mean and maximum flow.