Using stable isotopes to estimate travel times in a data-sparse Arctic catchment: Challenges and possible solutions

Area of Science:

• Hydrology
• Environmental Science
• Geochemistry

Background:

• Isotope tracers offer insights into catchment hydrology and biogeochemical transport.
• Permafrost catchments are understudied despite rapid environmental change in Arctic regions.
• Unique hydrological conditions in permafrost zones challenge traditional transit time estimations.

Purpose of the Study:

• To assess water travel times in a western Canadian Arctic permafrost catchment using an isotope-based approach.
• To investigate the influence of snowmelt, ice thaw, and rainfall on catchment hydrology.
• To evaluate the effectiveness of model-data fusion for estimating hydrological dynamics in permafrost environments.

Main Methods:

• Employed a model-data fusion approach to estimate snowpack and meltwater volumes and isotopic signatures.
• Collected and analyzed water samples (snowmelt, soil water, stream water, rainfall) for isotopic composition.
• Monitored soil moisture dynamics and active layer development throughout the sampling period.

Main Results:

• Transit time estimates were most accurate when incorporating all inflows: snowmelt, soil ice thaw, and rainfall.
• Early spring transit times were short, driven by snowmelt and ice thaw in frozen soils.
• Summer conditions showed increased mixing with active layer water, leading to longer mean travel times (~1.5 years).

Conclusions:

• Water travel times in permafrost catchments are highly dynamic, influenced by seasonal freeze-thaw cycles and active layer development.
• Accurate hydrological modeling in these regions requires integrating multiple water sources and seasonal variations.
• Further data collection is crucial for refining transit time estimates in permafrost-affected catchments.