Suspended sediment source and propagation during monsoon events across nested sub-catchments with contrasted land uses in LaosReport as inadecuate




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* Corresponding author 1 IEES - Institut d-écologie et des sciences de l-environnement de Paris 2 LSCE - Laboratoire des Sciences du Climat et de l-Environnement Gif-sur-Yvette 3 NAFRI - National Agriculture and Forestry Research Institute 4 DALaM - Department of Agricultural Land Management 5 GET - Géosciences Environnement Toulouse

Abstract : Study regionHouay Xon catchment in northern Laos.Study focusBecause agricultural headwater catchments of SE Asia are prone to erosion and deliver a significant proportion of the total suspended sediment supply to major rivers and floodplains, the potential sources of sediments and their dynamics were studied for two successive storm flow events in June 2013. Characterization of suspended sediment loads was carried out along a continuum of 7 monitoring stations, combining analyses of fallout radionuclides, particle borne organic matter and stream water properties.New hydrological insightsRadionuclide activities showed that remobilization of soil particles deposited during the previous rainy season or supplied by riverbank erosion is the dominant process, although pulses of surface-soil derived sediments also propagate downstream. This interpretation is supported by suspended organic matter data that also fingerprints the mixing of surface soil vs. subsurface particles. The study moreover highlights the advantages and the drawbacks of combining fallout radionuclides, particle borne organic matter composition and stream water characteristics to discriminate and quantify sediment sources and dynamics in rural areas undergoing urban sprawl.

Keywords : Suspended sediments 137Cs 210Pbxs 7Be Total organic matter composition





Author: Sylvain Huon - Olivier Evrard - Elian Gourdin - Irène Lefèvre - Thierry Bariac - Jean-Louis Reyss - Thierry Henry Des Tureaux -

Source: https://hal.archives-ouvertes.fr/



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