Transit Time Distributions on a Boreal Catchment Using a 14 Year Data Time Series.

Estimates of catchment water transit time provide powerful insight into hydrological and biogeochemical behaviors throughout and across seasons. In boreal catchments, transit time may be influenced by precipitation patterns and/or by differences in catchment structure that influence water storage. Resolving how these factors interact is critical for predicting transit time patterns in heterogeneous catchments. A recent study from a mixed forest/wetland catchment (C7) suggested that rain inputs during the snow-free season may regulate the long-term (10 year) inter-annual differences in mean annual water transit time. However, this model was based on a non-variant transit time, assuming that discharge was equal to precipitation input acting as a piston flow, and ignoring the existing interaction with storage water. As such, the model did not ensure water balance and was unable to capture the importance of inter-annual variation. To verify these results and overcome the limitations of that study, we are estimating the mean transit time of the water in the same catchment in northern Sweden, C7 in the Krycklan catchment using a time-variant model that includes storage selection functions in a 14 year data time series. The results from this study will provide a better understanding how a boreal landscape interacts with climate variability to shape transit times in boreal catchments using a long term record.