Modeling nonlinear responses of DOC transport in boreal catchments in Sweden. Issue 7 (2nd July 2016)

• Record Type: Journal Article
• Authors: Kasurinen, Ville; Alfredsen, Knut; Ojala, Anne; Pumpanen, Jukka; Weyhenmeyer, Gesa A.; Futter, Martyn N.; Laudon, Hjalmar; Berninger, Frank
• Is Part Of: Water resources research. Volume 52:Issue 7(2016:Jul.)
• Page Start: 4970
• Page End: 4989
• Publication Date: 2016-07-02
• Subjects: DOC -- hydrology -- Boreal catchments; Hydrology -- Periodicals; 333.91
• DOI: 10.1002/2015WR018343
• Languages: English
• ISSNs: 0043-1397

Abstract

Abstract: Stream water dissolved organic carbon (DOC) concentrations display high spatial and temporal variation in boreal catchments. Understanding and predicting these patterns is a challenge with great implications for water quality projections and carbon balance estimates. Although several biogeochemical models have been used to estimate stream water DOC dynamics, model biases common during both rain and snow melt‐driven events. The parsimonious DOC‐model, K‐DOC, with 10 calibrated parameters, uses a nonlinear discharge and catchment water storage relationship including soil temperature dependencies of DOC release and consumption. K‐DOC was used to estimate the stream water DOC concentrations over 5 years for eighteen nested boreal catchments having total area of 68 km 2 (varying from 0.04 to 67.9 km 2 ). The model successfully simulated DOC concentrations during base flow conditions, as well as, hydrological events in catchments dominated by organic and mineral soils reaching NSEs from 0.46 to 0.76. Our semimechanistic model was parsimonious enough to have all parameters estimated using statistical methods. We did not find any clear differences between forest and mire‐dominated catchments that could be explained by soil type or tree species composition. However, parameters controlling slow release and consumption of DOC from soil water behaved differently for small headwater catchments (less than 2 km 2 ) than for those that integrate larger areas of different ecosystem types (10–68 km 2 ). Our results emphasize that it is important to account for nonlinear dependencies of both, soil temperature, and catchment water storage, when simulating DOC dynamics of boreal catchments. Key Points: Used model replicated well DOC concentrations during hydrological events The use of soil temperature managed to separate snowmelt‐based DOC events from those occurred after the melt Simulated DOC and nonlinear catchment response to environmental forcing for 18 subcatchments