Modeling the effects of land use on dissolved organic carbon in boreal catchments using the HYPE model

Terrestrial carbon is a crucial source of streamflow dissolved organic carbon (DOC) in catchments. Within river catchments, land use types strongly affect the soil physical and chemical properties, shaping DOC formation, storage, and transport processes. Understanding the relationship between land use types and DOC dynamics is essential for predicting carbon fluxes and mitigating the adverse effects of land use changes on aquatic environments. This study aims to improve the Hydrological Predictions for the Environment (HYPE) model to quantify DOC contributions from different land use. The current HYPE model does not distinct land use type in some DOC processes (e.g., runoff delay.) Our work is to improve the DOC module in HYPE to investigate the land use effects on DOC-related processes from terrestrial to aquatic ecosystems. The DOC processes in each land use type will be characterized by a unique parameter set, which will account for variations in soil organic carbon content, microbial activity, and hydrological transport processes. This approach enables the HYPE model to capture the unique DOC dynamics associated with different land use types. The improved model will be applied and evaluated in the boreal Krycklan catchment in northern Sweden, a region dominated by forests but also including other land use types, such as wetlands and agricultural lands. We aim to answer the research question: How do different land use types influence DOC concentrations in streamflow within boreal catchments? Characterizing the spatiotemporal patterns of DOC contributions from each land use type will provide new insights into the interactions between the terrestrial and aquatic carbon cycling. Additionally, scenarios modeling will allow us to more reliably predict how future changes in land use may affect DOC concentrations and water quality in boreal catchments. Insights derived from this study will provide decision support for sustainable land and water resources management to mitigate the adverse effects of land use changes on aquatic ecosystems.