%0 Journal Article
%T Changes in discharge and solute dynamics between hillslope and valley-bottom intermittent streams
%A S. Bernal
%A F. Sabater
%J Hydrology and Earth System Sciences (HESS) & Discussions (HESSD)
%D 2012
%I Copernicus Publications
%X 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¨C70% between the hillslope and valley-bottom catchments during wet periods. During transition periods, stream solute export decreased by 34¨C97% 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 ¡À 0.12 kg N ha 1 yr 1 [average ¡À standard deviation]) was 30¨C50% lower than from the hillslope catchment (0.56 ¡À 0.32 kg N ha 1 yr 1). The annual export of dissolved organic carbon was similar between the two catchments (1.8 ¡À 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.
%U http://www.hydrol-earth-syst-sci.net/16/1595/2012/hess-16-1595-2012.html