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| Titel |
Test of a simplified modeling approach for nitrogen transfer in agricultural subsurface-drained catchments |
| VerfasserIn |
Hocine Henine, Julien Tournebize, Pärn Jaan, Mander Ülo |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148925
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| Publikation (Nr.) |
 EGU/EGU2017-13230.pdf |
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| Zusammenfassung |
| In agricultural areas, nitrogen (N) pollution load to surface waters depends on land use,
agricultural practices, harvested N output, as well as the hydrology and climate of the
catchment. Most of N transfer models need to use large complex data sets, which are
generally difficult to collect at larger scale (>km2). The main objective of this study is to
carry out a hydrological and a geochemistry modeling by using a simplified data set (land
use/crop, fertilizer input, N losses from plots).
The modelling approach was tested in the subsurface-drained Orgeval catchment (Paris
Basin, France) based on following assumptions:
Subsurface tile drains are considered as a giant lysimeter system. N concentration
in drain outlets is representative for agricultural practices upstream.
Analysis of observed N load (90% of total N) shows 62% of export during the
winter.
We considered prewinter nitrate (NO3) pool (PWNP) in soils at the beginning of
hydrological drainage season as a driving factor for N losses. PWNP results from
the part of NO3 not used by crops or the mineralization part of organic matter
during the preceding summer and autumn.
Considering these assumptions, we used PWNP as simplified input data for the modelling of N
transport. Thus, NO3 losses are mainly influenced by the denitrification capacity of soils and
stream water. The well-known HYPE model was used to perform water and N losses
modelling. The hydrological simulation was calibrated with the observation data at different
sub-catchments. We performed a hydrograph separation validated on the thermal and isotopic
tracer studies and the general knowledge of the behavior of Orgeval catchment. Our results
show a good correlation between the model and the observations (a Nash–Sutcliffe coefficient
of 0.75 for water discharge and 0.7 for N flux). Likewise, comparison of calibrated PWNP
values with the results from a field survey (annual PWNP campaign) showed significant
positive correlation. One can conclude that the simplified modeling approach using
PWNP as a driving factor for the evaluation of N losses from drained agricultural
catchments gave satisfactory results and we can propose this approach for a wider use. |
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