Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1029/2021WR031587
Licence creative commons licence
Title (Primary) Characterizing catchment-scale nitrogen legacies and constraining their uncertainties
Author Sarrazin, F.J.; Kumar, R. ORCID logo ; Basu, N.B.; Musolff, A.; Weber, M.; Van Meter, K.J.; Attinger, S.
Source Titel Water Resources Research
Year 2022
Department CHS; HDG
Volume 58
Issue 4
Page From e2021WR031587
Language englisch
Topic T5 Future Landscapes
T4 Coastal System
Keywords nitrogen legacies; water quality modeling; equifinality; parameter estimation; sensitivity analysis
Abstract Improving nitrogen (N) status in European water bodies is a pressing issue. N levels depend not only on current but also past N inputs to the landscape, that have accumulated through time in legacy stores (e.g. soil, groundwater). Catchment-scale N models, that are commonly used to investigate in-stream N levels, rarely examine the magnitude and dynamics of legacy components. This study aims to gain a better understanding of the long-term fate of the N inputs and its uncertainties, using a legacy-driven N model (ELEMeNT) in Germany’s largest national river basin (Weser; 38,450 km2) over the period 1960–2015. We estimate the nine model parameters based on a progressive constraining strategy, to assess the value of different observational datasets. We demonstrate that beyond in-stream N loading, soil N content and in-stream N concentration allow to reduce the equifinality in model parameterizations. We find that more than 50% of the N surplus denitrifies (1480–2210 kg ha−1) and the stream export amounts to around 18% (410–640 kg ha−1), leaving behind as much as around 230–780 kg ha−1 of N in the (soil) source zone and 10–105 kg ha−1 in the subsurface. A sensitivity analysis reveals the importance of different factors affecting the residual uncertainties in simulated N legacies, namely hydrologic travel time, denitrification rates, a coefficient characterising the protection of organic N in source zone and N surplus input. Our study calls for proper consideration of uncertainties in N legacy characterization, and discusses possible avenues to further reduce the equifinality in water quality modelling.
Persistent UFZ Identifier
Sarrazin, F.J., Kumar, R., Basu, N.B., Musolff, A., Weber, M., Van Meter, K.J., Attinger, S. (2022):
Characterizing catchment-scale nitrogen legacies and constraining their uncertainties
Water Resour. Res. 58 (4), e2021WR031587 10.1029/2021WR031587