Aarhus Universitets segl

No. 115: Freshwater and nutrient inputs to the Limfjorden based on three different catchment models

Thodsen H, Molina-Navarro E, Nielsen JW, Larsen J, Maar M. (2018) Afstrømning og næringsstoftilførsler til Limfjorden baseret på tre forskellige modeller. Aarhus Universitet, DCE – Nationalt Center for Miljø og Energi, 20 s. - Teknisk rapport fra DCE - Nationalt Center for Miljø og Energi nr. 115.
http://dce2.au.dk/pub/TR115.pdf

Summary

The report compares estimated freshwater and nutrient inputs to the Limfjorden based on three different catchment models and evaluates their suitability as input to marine models. In the national, empirical model DK-QNP, approximately half of the catchment is monitored and is assumed to give the most reliable results among the three models. The DK-QNP model, however, has a rather coarse spatiotemporal (monthly) resolution compared to the other two dynamic models, SWAT and E-HYPE. The estimated freshwater inputs between the three models were nevertheless similar and indicate a good simulation of the water balance in the whole Limfjord. TN-inputs were overestimated by SWAT, whereas TP inputs were underestimated by E-HYPE compared to DK-QNP. The seasonal patterns of the inputs were similar between the models with the highest input during winter and the lowest input during summer. The locally calibrated model SWAT had the highest amount of freshwater sources included, daily time-steps and several nutrient fractions, which all together made it the most suitable model for providing input to marine ecological models. However, the bias of TN-values in SWAT was corrected against the DK-QNP levels. E-HYPE had the highest geographical coverage and was used as input to the hydrodynamic model HBM for the Limfjorden, which is a part of a larger model system for the North Sea-Baltic Sea.