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| Titel |
C-GEM (v 1.0): a new, cost-efficient biogeochemical model for estuaries and its application to a funnel-shaped system |
| VerfasserIn |
C. Volta, S. Arndt, H. H. G. Savenije, G. G. Laruelle, P. Regnier |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 7, no. 4 ; Nr. 7, no. 4 (2014-07-04), S.1271-1295 |
| Datensatznummer |
250115654
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| Publikation (Nr.) |
 copernicus.org/gmd-7-1271-2014.pdf |
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| Zusammenfassung |
| Reactive transport models (RTMs)
are powerful tools for disentangling the complex process interplay that
drives estuarine biogeochemical dynamics, for assessing the quantitative role
of estuaries in global biogeochemical cycles and for predicting their
response to anthropogenic disturbances (land-use change, climate change and
water management). Nevertheless, the application of RTMs for a regional or
global estimation of estuarine biogeochemical transformations and fluxes is
generally compromised by their high computational and data demands. Here, we
describe C-GEM (Carbon-Generic Estuary Model), a new one-dimensional,
computationally efficient RTM that reduces data requirements by using a
generic, theoretical framework based on the direct relationship between
estuarine geometry and hydrodynamics. Despite its efficiency, it provides an
accurate description of estuarine hydrodynamics, salt transport and
biogeochemistry on the appropriate spatio–temporal scales. We provide a
detailed description of the model, as well as a protocol for its set-up. The
new model is then applied to the funnel-shaped Scheldt estuary (BE/NL), one
of the best-surveyed estuarine systems in the world. Its performance is
evaluated through comprehensive model–data and model–model comparisons.
Model results show that C-GEM captures the dominant features of the
biogeochemical cycling in the Scheldt estuary. Longitudinal steady-state
profiles of oxygen, ammonium, nitrate and silica are generally in good
agreement with measured data. In addition, simulated, system-wide integrated
reaction rates of the main pelagic biogeochemical processes are comparable
with those obtained using a high-resolved, two-dimensional RTM. A
comparison of fully transient simulations results with those of a
two-dimensional model shows that the estuarine net ecosystem metabolism (NEM)
only differs by about 10%, while system-wide estimates of individual
biogeochemical processes never diverge by more than 40%. A sensitivity
analysis is carried out to assess the sensitivity of biogeochemical processes
to uncertainties in parameter values. Results reveal that the geometric
parameters LC (estuarine convergence length) and H (water depth), as well
as the rate constant of organic matter degradation (kox) exert an
important influence on the biogeochemical functioning of the estuary. The
sensitivity results also show that, currently, the most important hurdle
towards regional- or global-scale applications arises from the lack of an
objective framework for sediment and biogeochemical process parameterization.
They, therefore, emphasize the need for a global compilation of
biogeochemical parameter values that can help identify common trends and
possible relationships between parameters and controlling factors, such as
climate, catchment characteristics and anthropic pressure. |
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