Publication Details |
| Category | Text Publication |
| Reference Category | Journals |
| DOI | 10.1029/2021WR031587 |
Licence  |
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| Title (Primary) | Characterizing catchment-scale nitrogen legacies and constraining their uncertainties |
| Author | Sarrazin, F.J.; Kumar, R.
; 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 |
| Supplements | Supplement 1 |
| 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. |
| 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 |
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