 |
| Titel |
Evaluation and interpretation of regional and site-specific hydrochemical data bases for water quality assessment |
| VerfasserIn |
M. G. Hutchins, B. Reynolds, B. Smith, G. N. Wiggans, T. R. Lister |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1027-5606
|
| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 3, no. 4 ; Nr. 3, no. 4, S.565-580 |
| Datensatznummer |
250001192
|
| Publikation (Nr.) |
 copernicus.org/hess-3-565-1999.pdf |
|
|
|
|
|
| Zusammenfassung |
The spatial distribution of stream water
composition, as determined by the Geochemical Baseline Survey of the Environment
(G-BASE) conducted by the British Geological Survey (BGS) can be successfully
related under baseflow conditions to bedrock geochemistry. Further consideration
of results in conjunction with site-specific monitoring data enables factors
controlling both spatial and temporal variability in major element composition
to be highlighted and allows the value of the survey to be enhanced. Hence,
chemical data (i) from streams located on Lower Silurian (Llandovery) bedrock at
1 km2 resolution collected as part of the G-BASE survey of Wales and the West
Midlands and (ii) from catchment monitoring studies located in upland mid-Wales
(conducted by Institute of Terrestrial Ecology), have been considered together
as an example.
Classification of the spatial survey data set
in terms of potentially controlling factors was carried out so as to illustrate
the level of explanation they could give in terms of observed spatial chemical
variability. It was therefore hypothesised that on a geological
lithostratigraphic series of limited geochemical contrast, altitude and land-use
factors provide better explanation of this variability than others such as
lithology at sampling site and stream order. At an individual site, temporal
variability was also found to be of considerable significance and, at a monthly
time-step, is explicable in terms of factors such as antecedent conditions and
seasonality. Data suggest that the degree of this variability may show some
relationship with stream order and land-use. Monitoring data from the region
also reveal that relationships between stream chemistry and land-use may prove
to be strong not only at base flow but also in storm flow conditions.
In a wider context, predictions of the
sensitivity of stream water to acidification based on classifications of soil
and geology are successful on a regional scale. However, the study undertaken
here has shown that use of such classification schemes on a catchment scale
results in considerable uncertainty associated with prediction. Uncertainties
are due to the large degree of variability in stream chemistry encountered both
spatially within geological units and temporally at individual sampling sites. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|