To gain understanding on how alluvial zones modify water and nutrient export from semiarid catchments, we compared monthly discharge as well as stream chloride, carbon, and nitrogen dynamics between a hillslope catchment and a valley-bottom catchment with a well-developed alluvium. Stream water and solute fluxes from the hillslope and valley-bottom catchments showed contrasting patterns between hydrological transitions and wet periods, especially for bio-reactive solutes. During transition periods, stream water export decreased >40% between the hillslope and the valley bottom coinciding with the prevalence of stream-to-aquifer fluxes at the alluvial zone. In contrast, stream water export increased by 20-70% between the hillslope and valley-bottom catchments during wet periods. During transition periods, stream solute export decreased by 34-97% between the hillslope and valley-bottom catchments for chloride, nitrate, and dissolved organic carbon. In annual terms, stream nitrate export from the valley-bottom catchment (0.32 ± 0.12 kg N ha -1 yr-1 [average ± standard deviation]) was 30-50% lower than from the hillslope catchment (0.56 ± 0.32 kg N ha-1 yr-1). The annual export of dissolved organic carbon was similar between the two catchments (1.8 ± 1 kg C ha-1 yr -1). Our results suggest that hydrological retention in the alluvial zone contributed to reduce stream water and solute export from the valley-bottom catchment during hydrological transition periods when hydrological connectivity between the hillslope and the valley bottom was low.© 2012 Author(s). CC Attribution 3.0 License.
CITATION STYLE
Bernal, S., & Sabater, F. (2012). Changes in discharge and solute dynamics between hillslope and valley-bottom intermittent streams. Hydrology and Earth System Sciences, 16(6), 1595–1605. https://doi.org/10.5194/hess-16-1595-2012
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