CaMP-DOC v1.0: A process-based model for quantifying dissolved organic carbon fluxes in wetland-dominated catchments

Dissolved organic carbon (DOC) is a key, yet poorly reported component of the terrestrial carbon cycle and an important link between land and aquatic ecosystems. Despite its significance, DOC export from wetlands remains largely excluded from national carbon accounting frameworks, including Canada’s, due to substantial uncertainty in regional flux estimates. Here we present CaMP-DOC, a process-based model that simulates DOC dynamics in peatland-dominated ecosystems by explicitly coupling hydrological drivers with soil biogeochemical processes. CaMP-DOC extends the Canadian Model for Peatlands (CaMP) by incorporating a DOC module that represents soil DOC production, consumption, leaching, and aquatic losses regulated by water residence time. The model was evaluated using a well-characterized catchment (Tributary 5A) within the Attawapiskat watershed of the Hudson Bay Lowlands. The simulations were compared against multi-year observations of peat pore-water DOC concentrations, stream DOC concentrations, net ecosystem exchange, water table depth, and runoff. CaMP-DOC successfully reproduced observed hydrological data and peat porewater and stream DOC concentrations. By explicitly representing lateral DOC export, CaMP-DOC provides a parsimonious yet mechanistic tool for improving regional and national wetland carbon budgets compatible with IPCC guidelines. The model is flexible to accommodate future integration of lateral carbon fluxes from non-wetland ecosystems such as upland forests.