The role of lithology,catchment size and the alluvial zone on the hydrogeochemistry of two intermittent Mediterranean streams |
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| Authors: | Susana Bernal Francesc Sabater |
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| Institution: | 1. Department of Ecology and Evolutionary Biology, Princeton University. Guyot Hall, 08544 Princeton, New Jersey, USA;2. Department of Ecology, Faculty of Biology, University of Barcelona, Diagonal 645, 08028 Barcelona, Spain |
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| Abstract: | Hydrology and solute concentrations of two intermittent Mediterranean streams draining two nested catchments were compared. The two catchments were mainly underlain by granitic rocks and different types of sericitic schists. Only the lowland catchment had an alluvial zone and a well‐developed riparian forest. The rainfall–runoff relationship and the correlation between daily flow concentrations showed that hydrological behaviour was similar at both sites during most of the year. However, reverse fluxes were detected during the wetting and drying up periods only in the stream with an alluvial zone. The intermittence in stream flow also had effects on absolute solute concentrations, temporal solute dynamics and streamwater stoichiometry. Streamwater chemistry was not affected by drainage area, except for cations produced mainly by bedrock dissolution (i.e. calcium and magnesium) that increased with increasing catchment size. Differences in the relationship among cations and anions were detected between the two streams, which could be attributed to biogeochemical processes occurring in the alluvial zone. The multivariate model used in this study showed that stoichiometry was more useful than absolute concentrations when analyzing the influence of different lithologies on streamwater chemistry. Such differences were amplified in autumn, likely due to a low hydrological connectivity between the two nested catchments. Copyright © 2007 John Wiley & Sons, Ltd. |
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| Keywords: | alluvial zone catchment size hydrology intermittent stream lithology streamwater chemistry |
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