Combining multiple fallout radionuclides (¹³⁷Cs, ⁷Be, ²¹⁰Pb_xs) improves our understanding of sediment source dynamics in tropical rivers

Olivier Evrard (1, 2) , J. Patrick Laceby (1, 2) , Sylvain Huon (3) , Irène Lefevre (1, 2) , Oloth Sengtaheuanghoung (4) , Olivier Ribolzi (5)

1 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
2 GEDI - Géochimie Des Impacts
3 Bioemco - Biogéochimie et écologie des milieux continentaux
4 NAFRI
5 GET - Géosciences Environnement Toulouse

Soil erosion has accelerated as a result of land use change, increasing the sediment supply to rivers worldwide. A thorough knowledge of sediment dynamics is required to design efficient management measures to control erosion and reduce sediment delivery from catchments. Fallout radionuclides are often used separately to provide spatial ($^{137}$Cs) or temporal ($^7$Be, $^{210}$Pb$_{xs}$) information on sediment sources. In this study, we examine their combined application to simultaneously model spatial and temporal sediment source dynamics. To this end, potential sediment sources (n=84) and suspended sediment (n=16) were collected at two stations in a 12 km² catchment in Northern Laos during the first flood of the 2014 wet season. Part of the source material was directly sampled in ephemeral flow occurring on hillslopes to avoid the grain size selectivity problems that may occur during erosion and river transport processes

Domaines: Sciences de l'environnement; Milieux et Changements globaux; Interfaces continentales, environnement; Géomorphologie; Hydrologie; Science des sols

Olivier Evrard, J. Patrick Laceby, Sylvain Huon, Irène Lefevre, Oloth Sengtaheuanghoung, et al.. Combining multiple fallout radionuclides (¹³⁷Cs, ⁷Be, ²¹⁰Pb_xs) improves our understanding of sediment source dynamics in tropical rivers. AGU Fall Meeting 2015, Dec 2015, San Francisco, United States. ⟨cea-02669217⟩