Open Collections

Barrera Mosquera, Diana Melissa

University of British Columbia

Floodplains are important organic carbon (OC) storage sites, and the evolution of watercourses modulates the transport, burial, and reworking of organic matter with cascading effects on watershed CO₂ budgets. The migration of adjacent channels can transport and bury OC that is then preserved in reducing environments. If OC is later exposed subaerially, it undergoes oxidation by reacting with oxygen – a reaction that de facto reverses photosynthesis and releases carbon dioxide (CO₂) back into the atmosphere. Imbalances between burial and oxidation can modulate watershed CO₂ budgets, such that it is important to establish models of OC sequestration and export by rivers. Meandering rivers have broadly predictable patterns of channel-planform evolution, providing an opportunity to assess floodplain OC budgets in relation to characteristic migration rates and floodplain ages. However, complexities associated with the natural geomorphic variability of meandering rivers has delayed the assessment of quantitative relationships between channel and OC dynamics. We illustrate evolving OC budgets in relation to channel migration in the Vermilion River (Ontario) located in the boreal forest of eastern North America. We combine photogrammetric analyses and dynamic time warping of channel centrelines with analysis of top-soil bulk density and OC. We found that variations of OC stock per unit surface area and soil development are modulated by meander migration through the development of typical boreal-forest vegetation successions. Furthermore, we explained the observed dependency of channel migration rate to integration timescale in terms of occasional occurrence of migration reversals, imprecisions in imagery’s georeferencing, and intermittent bankfull discharge stages. Our results provide a quantification of the degree to which meander migration controls soil development, forest age, and floodplain OC budgets over characteristic timescales related to meander growth and abandonment. We anticipate our study to inform wider applications to rivers in different biogeoclimatic zones – an approach that may in turn help carbon assessment in the context of changing climate or land use.

Text

2024-01-15

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/87284

Earth and Environmental Sciences

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/