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| Titel |
A hydrochemical modelling framework for combined assessment of spatial and temporal variability in stream chemistry: application to Plynlimon, Wales |
| VerfasserIn |
H. J. Foster, M. J. Lees, H. S. Wheater, C. Neal, B. Reynolds |
| 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 ; 5, no. 1 ; Nr. 5, no. 1, S.49-58 |
| Datensatznummer |
250002254
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| Publikation (Nr.) |
 copernicus.org/hess-5-49-2001.pdf |
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| Zusammenfassung |
| Recent concern about the risk to biota from
acidification in upland areas, due to air pollution and land-use change (such as
the planting of coniferous forests), has generated a need to model catchment
hydro-chemistry to assess environmental risk and define protection strategies.
Previous approaches have tended to concentrate on quantifying either spatial
variability at a regional scale or temporal variability at a given location.
However, to protect biota from ‘acid episodes’, an assessment of both
temporal and spatial variability of stream chemistry is required at a catchment
scale. In addition, quantification of temporal variability needs to represent
both episodic event response and long term variability caused by deposition
and/or land-use change. Both spatial and temporal variability in streamwater
chemistry are considered in a new modelling methodology based on application to
the Plynlimon catchments, central Wales. A two-component End-Member Mixing
Analysis (EMMA) is used whereby low and high flow chemistry are taken to
represent ‘groundwater’ and ‘soil water’ end-members. The conventional
EMMA method is extended to incorporate spatial variability in the two
end-members across the catchments by quantifying the Acid Neutralisation
Capacity (ANC) of each in terms of a statistical distribution. These are then
input as stochastic variables to a two-component mixing model, thereby
accounting for variability of ANC both spatially and temporally. The model is
coupled to a long-term acidification model (MAGIC) to predict the evolution of
the end members and, hence, the response to future scenarios. The results can be
plotted as a function of time and space, which enables better assessment of the
likely effects of pollution deposition or land-use changes in the future on the
stream chemistry than current methods which use catchment average values. The
model is also a useful basis for further research into linkage between
hydrochemistry and intra-catchment biological diversity.
Keywords: hydrochemistry, End-Member Mixing Analysis (EMMA), uplands, acidification |
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