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| Titel |
Importance of stream temperature to climate change impact on water quality |
| VerfasserIn |
A. Ducharne |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 12, no. 3 ; Nr. 12, no. 3 (2008-05-23), S.797-810 |
| Datensatznummer |
250010658
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| Publikation (Nr.) |
 copernicus.org/hess-12-797-2008.pdf |
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| Zusammenfassung |
| The sensitivity of some aspects of water quality to climate change was
assessed in the Seine River (France) with the biogeochemical model
RIVERSTRAHLER, which describes the transformations and fluxes of C, N, P and
Si between the main microbiological populations, the water column and the
sediment, along the entire river network. Point and diffuse sources are
prescribed, stream temperature undergoes a sinusoidal annual cycle
constrained by observations, and runoff is calculated by a physically-based
land surface model. The reference simulation, using meteorological forcing
of 1986–1990 and point sources of 1991, compares very well with
observations. The climate change simulated by a general circulation model
under the SRES emission scenario A2 was used to simulate the related changes
in runoff and stream temperature. To this end, a statistical analysis was
undertaken of the relationships between the water and air temperatures in
the Seine watershed over 1993–1999, using 88 points that correctly sampled
the variability of the tributaries. Most of stream temperature variance was
explained by the lagged moving average of air temperature, with parameters
that depended on Strahler stream order. As an interesting simplification,
stream temperature changes could be approximated by air temperature changes.
This modelling framework was used to analyse of the relative influence of
the water warming and discharge reduction induced by climate change on
biogeochemical water quality in Paris and downstream. Discharge reduction
increased phytoplankton growth and oxygen deficits. Water warming decreased
dissolved oxygen, increased phytoplankton biomass during the growth period,
and reduced it afterwards, when loss factors dominate. It was also shown
that these impacts were enhanced when point source inputs of nutrient and
organic carbon increased. |
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