Linking Dominant Rainfall‐Runoff Event Hydrologic Response Dynamics With Nitrate and Chloride Load Estimates of Three Boreal Shield Catchments

다국어 초록 (Multilingual Abstract)

Understanding hydrological dynamics in boreal Shield catchments is critical for projecting changes in stream runoff and chemistry in a region that is, sensitive to climate change. Previous work has mostly focused on a limited number of events over one or a few seasons because of the relative scarcity of high‐frequency datasets and automated tools for rainfall‐runoff event delineation. For the boreal region, a greater understanding of seasonality in hydrologic response and solute export related to rainfall‐initiated events is needed, as significant shifts in hydrologic regimes from climate change are expected. This study aimed to help resolve these knowledge gaps by assessing event‐scale hydrologic response dynamics and stream loads of nitrate and chloride using long‐term data from three boreal Shield catchments. Hydrometric and stream chemistry data from 2001 to 2018 were analyzed to delineate rainfall‐runoff events and estimate event nitrate and chloride loads. Event hydrologic response and loads were highly variable, especially with respect to catchment runoff initiation. Only subtle differences in hydrologic response dynamics were observed between summer and fall events, while seasonal differences in event nitrate and chloride loads were most statistically significant. Interestingly, a wide range of rainfall‐runoff events classified by response magnitude and timing was associated with differences in nitrate and chloride export. This study further confirms the utility of long‐term high‐frequency datasets and illustrates the need for additional work to further assess long‐term changes in event‐based hydrologic response and stream solute concentrations in the boreal region.
The boreal region is a vast mosaic of freshwater resources, including wetlands, streams, and lakes. The movement of water and solutes through catchments in this region is very sensitive to climate change, making it critical to understand the controls on these processes. Rainfall events are very important for transporting water and solutes from catchments to streams and are particularly sensitive to changes in climate. It is difficult to understand event‐scale dynamics since long records and high‐frequency datasets are not common and take a long time to process. The goal of this study was to look at event‐scale chloride and nitrate dynamics from a long‐term study site using recently‐developed tools for delineating events. There was a lot of variability in streamflow responses to events, and summer and fall events were somewhat similar. There was a wide range of nitrate and chloride export associated with events, and some of the variability had to do not just with the magnitude of the event, but also with the timing. This study highlights the value of collecting high‐frequency datasets at long‐term study sites in order to understand the impacts of climate change in the boreal region.



Rainfall‐runoff event analysis at boreal Shield catchments indicated significant temporal variability in hydrologic response & solute export

Leveraging newly available tools for quasi‐automated rainfall‐runoff event delineation allows new insights to be gleaned from long‐term data

Classes of rainfall‐runoff events characterized by response magnitude & timing are associated with significant differences in solute export


Rainfall‐runoff event analysis at boreal Shield catchments indicated significant temporal variability in hydrologic response & solute export
Leveraging newly available tools for quasi‐automated rainfall‐runoff event delineation allows new insights to be gleaned from long‐term data
Classes of rainfall‐runoff events characterized by response magnitude & timing are associated with significant differences in solute export