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| Titel |
Modelling regional response of lakewater chemistry to changes in acidic deposition: the MAGIC model applied to lake surveys in southernmost Norway 1974-1986-1995 |
| VerfasserIn |
B. J. Cosby, R. F. Wright |
| 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 ; 2, no. 4 ; Nr. 2, no. 4, S.563-576 |
| Datensatznummer |
250000653
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| Publikation (Nr.) |
 copernicus.org/hess-2-563-1998.pdf |
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| Zusammenfassung |
Two methods for modelling regional responses of lake water
quality to changes in acidic deposition in southernmost Norway were examined. Both methods
are based upon the MAGIC model but differ in mode of regional application; one uses
site-specific while the other uses Monte-Carlo methods for model calibration. The
simulations of regional responses from both methods were compared with observed responses
based on data from three lake surveys in southernmost Norway conducted in 1974, 1986 and
1995.
The regional responses of the two modelling approaches were quite similar and agreed
well with the observed regional distributions of lakewater chemistry variables. From 1974
to 1986 the observed data indicated that despite a decline of approximately 10% in
sulphate (SO4) deposition, the mean acid neutralizing capacity (ANC) of lakes
in southernmost Norway declined by approximately 6 μeq l-1. Both modelling
approaches simulated no change or a very small decline in mean ANC for that period. From 1986
to 1995 the observed data indicated that, in response to an approximate 40% decline in
SO4 deposition, the mean ANC of
lakes in southernmost Norway increased by 11-16 μeq l-1. The modelling
approaches simulated increases of 9-10 μeq l-1 in mean ANC for the same period.
Both simulations and observations indicate that > 65% of lakes in southernmost Norway
were acidic in 1974 and 1995. Both simulation methods predict that >65% of the lakes
in southernmost Norway will have positive ANC values within 10 years of reductions of
SO4 deposition
to 20% of 1974 levels.
Of the two regionalization methods the site-specific method appears
preferable, because whereas the Monte-Carlo method gives results for a region as a whole,
the site-specific method also reveals patterns within the region. The maintenance of a
one-to-one correspondence between simulated and observed systems means that simulation
results can be mapped for a geographically explicit presentation of model results. The
ability to examine geographic patterns of response is becoming increasingly important in
regional assessments. |
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