Author(s): Luca Salerno; Matteo Bertagni; Carlo Camporeale

Linked Author(s): Carlo Camporeale

Keywords: Carbon cycle; Rivers; Stochastic processes; Riparian vegetation; Morphodynamics

Abstract: Rivers reshape their floodplains through coupled hydrological, sedimentological, and biological processes that drive riverine landscape evolution and global carbon fluxes (Drake et al., 2018). Riparian zones are highly sensitive to flow variability, which supplies vegetation with moisture, nutrients, and seeds through flooding and sediment deposition, but can also uproot it during extreme events. Together with photosynthetic carbon fixation by riparian vegetation, this recruitment, transport, and burial of biomass forms a two-step ecomorphodynamic carbon pumping (ECP) mechanism (Salerno et al., 2024) that moves carbon from the atmosphere to long-term reservoirs such as river sedimentary deposits and the ocean. The first step, ecomorphodynamic carbon export, recruits large-wood biomass through flood-induced uprooting, which may be retained or transported to the ocean; the second, enhanced net primary production, fixes carbon via vegetation encroachment on newly exposed riparian areas. The two steps generate compensating outgoing and incoming carbon fluxes. To assess how vegetation reworking under flow fluctuations controls riverine carbon pumping, we develop a stochastic framework coupling river morphodynamics, flow variability, and vegetation growth and uprooting. Applied to sand-bed and gravel-bed rivers through generalized hydraulic-geometry scaling, it enables a comparative analysis of ECP across contrasting fluvial environments.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.340

Year: 2026