Variations in Water Storage Capacity of a Mountain Peatland with Complex Stratigraphy

Abstract

Peatlands in the Rocky Mountains most commonly occur in valley bottoms and are classified as fens. Understanding how fens influence water storage and water release is essential for better predicting water availability as the climate changes. Peatlands located in mountain regions tend to have a complex soil profile due to the geomorphologically dynamic environment. There is little information on the water storage capacity of mountain peatlands. To address this knowledge gap, the water storage capacity of a fen peatland with a complex soil profile in the Canadian Rocky Mountains, Alberta, Canada, was studied. Using the water table fluctuation method, vertical variations in specific yield were estimated. The influence of several factors – soil profile complexity, vegetation cover, water table depth, and seasonality – on specific yield were determined. Results showed that soil profile complexity plays a vital role in determining the spatial variability of vertical specific yield. The effect of stratigraphy on specific is important because it demonstrates that active geomorphic environments (often found in mountain regions) are a crucial piece of information required to determine the water storage capacity of mountain fens. The seasonality analysis results show that the overall wetness of a given year or time during the growing season influences the water table depth and response to rainfall events, thus exerting a control on specific yield. The impact of seasonality is also important because it reveals that even small changes to weather patterns can impact water storage in mountain peatlands. Overall, the research yielded new insights into how much water is stored in and released from mountain fens, information which is useful to improving regional hydrological models and predicting hydrological impacts of climate change or geomorphic events.