Three approaches to estimate inorganic nitrogen loading under varying climatic conditions from a headwater catchment in Finland

Inorganic nitrogen loading was simulated using two dynamic catchment scale models, Integrated Nutrients in Catchments–Nitrogen (INCA-N) and the Generalized Watershed Loading Functions (GWLF). The simulated N loading was compared to a standard method to calculate annual loading using measured dischar...

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Bibliographic Details
Published inHydrology Research Vol. 40; no. 2-3; pp. 167 - 176
Main Authors Bärlund, I., Rankinen, K., Järvinen, M., Huitu, E., Veijalainen, N., Arvola, L.
Format Journal Article
LanguageEnglish
Published London IWA Publishing 2009
Subjects
Annual variations
Catchment area
Catchment areas
Catchment scale
Catchments
Climate change
Climatic conditions
Computer simulation
Discharge
Headwater catchments
Headwaters
Hydrologic models
Hydrology
Interannual variability
Mathematical analysis
Methods
Mineral nutrients
Nitrogen
Nutrients
Rain
Rainfall
Scale models
Snowmelt
Watersheds
Finland
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Summary:Inorganic nitrogen loading was simulated using two dynamic catchment scale models, Integrated Nutrients in Catchments–Nitrogen (INCA-N) and the Generalized Watershed Loading Functions (GWLF). The simulated N loading was compared to a standard method to calculate annual loading using measured discharge and discharge-weighted concentrations. The main aim of the study was to compare these three estimation approaches with regards to their performance in hydrologically variable years in a small headwater catchment in southern Finland. Inter-annual variability of INCA-N and GWLF was compared with measured inorganic N concentrations at the catchment outlet. In years where snow melt dominates the annual discharge pattern all methods gave concurrent annual loading estimates. However, the loading estimates differ between the studied methods in years where large rainfall events in late summer or autumn dominate the annual discharge pattern, or when the model was not able to reproduce the spring discharge maximum properly. The results suggest that both models can be useful tools in estimating dissolved inorganic nitrogen loading from a catchment under changing climate conditions, providing that the key influencing driver, hydrology, is well captured.
ISSN:0029-1277
1998-9563
2224-7955
DOI:10.2166/nh.2009.058