Predictions
in Ungauged Basins: Promise and Progress (Proceedings of symposium S7 held during the
Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS
Publ. 303, 2006, 21-29.
Using factor analysis and end-member mixing
techniques to infer sources of runoff generation
CORINNA ABESSER1,*, RUTH ROBINSON1 & CHRIS SOULSBY2
1 Department of Geography and Geosciences, University of St Andrews, St Andrews KY16 9AL, UK
2 Department of Geography and Environment, University of Aberdeen, Aberdeen AB24 3UF, UK
* now at: British Geological Survey, Maclean Building, Crowmarsh Gifford, Wallingford, OX10 8BB, UK
Abstract Factor analysis and (two-component) end member mixing analysis (EMMA) were applied to high resolution stream chemistry data from three catchments to infer sources of iron- and manganese-rich runoff in the catchment area and to evaluate their temporal and spatial influence on the streamwater quality. Two Fe and Mn sources were identified: (a) an organic soilwater source, associated with Fe and Mn accumulation in the organic-rich upper soil horizons; and (b) a deep soilwater/groundwater source arising from reduced metal mobilization in the deeper soils. While: (a) provides the dominant Fe and Mn inputs during storm events; (b) becomes important just before peak flow when riparian groundwater is displaced into the stream, giving rise to high Fe and Mn concentrations. The timing of such high Fe and Mn loadings in the stream runoff has important implications for the water supply management of the catchment.
Key words EMMA;
factor analysis; hydrology; iron; manganese; Scotland, UK