8. Conclusion#
8.1 Conclusion#
This study answers the research question: “How will climate change impact discharge in the Lower Athabasca River in Canada and what implications this has for navigation?” A critical discharge of 500 \(m^3/s\) was used to identify low flow conditions that will restrict navigation at 8 critical points in the river. This threshold was applied within a fixed open water season from 18 May to 17 October. The hydrological model HBV was calibrated and validated using discharge data at Fort McMurray and ERA5 forcing data. The model was then forced with CMIP6 climate data under climate scenarios SSP126, SSP245 and SSP370 to analyse future annual low flow days in this fixed open water season between 2025-2099.
The results indicate that future low flow days are generally higher than in the historical period. The observed period contains an average of 27 low flow days per year, while future periods range between 31 and 49 low flow days depending on the climate scenario. A clear long term increase over time is only visible under SSP370, approaching statistical significance with a p value of 0,054. However, the distribution of annual low flow days shows that extreme low flow years become more frequent in all climate scenarios. This may suggest that navigation in the LAR may become more restricted in the future, especially during longer periods where discharge falls below the critical threshold. This is particularly relevant for Indigenous communities that depend on the river for hunting, fishing, travel and transportation of resources.
The open water season is expected to expand under future climate scenarios. River ice break up occurs earlier in spring and freeze up occurs later in autumn. This may further impact communities if cold days where ice roads may be utilised are replaced by warmer days where navigation may be restricted due to low flows. Overall, climate change is expected to increase pressure on navigation in the LAR with the strongest impacts occurring under SSP370.
8.2 Future Recommendations#
Future research should focus on seasonal changes in navigation. The results show that winters become shorter and the open water season expands, but the effect of this on regional transportation needs to be further investigated. This could include analysing low flow days outside the fixed open water season used in this study, to assess whether earlier ice break up and later freeze up create additional periods of restricted navigation.
Future research should use an ensemble of climate models and hydrological models to better assess uncertainty in the projected low flow results.
Finally, future studies should also analyse high flow conditions and flood risk during the spring freshet. Earlier snowmelt and changing precipitation patterns may shift the timing and magnitude of high flows, which could influence flood risk and navigational controls in the LAR.