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5 results on '"Lionel Cottenot"'

1. Impacts of raindrops increase particle sedimentation in a sheet flow

Author

Amina Nouhou Bako, Lionel Cottenot, Pierre Courtemanche, Carine Lucas, François James, Frédéric Darboux, Unité de Science du Sol (Orléans) (URSols), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut Denis Poisson (IDP), Université d'Orléans (UO)-Université de Tours (UT)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Sols et Environnement (LSE), Université de Lorraine (UL)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), and The Région Centre-Val de Loire and INRAE funded the PhD fellowship of Amina Nouhou-Bako. The project 'Multiparticular transfer by overland flow' CNRS-INSU 2016 TelluS-INSMI-MI funded part of the experiments.

Subjects
experiment, overland flow, settling velocity, interrill, rainfall, Geography, Planning and Development, Earth and Planetary Sciences (miscellaneous), sediment flux, [SDV.SA.SDS]Life Sciences [q-bio]/Agricultural sciences/Soil study, Earth-Surface Processes
Abstract

International audience; Interrill erosion is driven by raindrops and sheet flow. Raindrop impacts cause sediment detachment and splash, but can also affect flow transport. Even if these processes have been studied for long, the actual effect of raindrop impacts on particle settling velocities has not been experimentally assessed. This leads to unconstrained adjustments in the soil erosion models, the settling velocity of particles being a freely adjustable parameter allowing for better fitting the particle flux measured at the outlet. To address the effect of raindrop impacts on the settling of particles in sheet flow, a laboratory flume experiment was designed, using an upstream feeder of sediment (100–200 μm) and simulated rainfalls. It reproduced conditions close to sheet flow, while not allowing for the detachment of particles from the flume bottom. Two series of experiments were run: a series with a high rainfall intensity (175 mm h−1) generated by an oscillating-nozzle rainfall simulator, and a series with lower rainfall intensities (10, 15, 25, 35, 55 mm h−1) generated by a drop-former rainfall simulator. When a rainfall was applied, it systematically decreased the sediment concentration at the outflow compared to the no rain condition, however no obvious relationship was found with the rainfall intensity. This shows that raindrop impacts increase particle settling velocities in sheet flow. Two underlying mechanisms are suggested, related to the momentum of the raindrops or to the turbulence caused by the raindrops into the flow. Further studies should be carried out, using computational fluid dynamics and collaboration with the fluid mechanics community.

Published
2022

2. Soil tillage impact on the relative contribution of dissolved, particulate and gaseous (CO2) carbon losses during rainstorms

Author

Frédéric Darboux, Hervé Gaillard, Katell Quenea, Maxdex Mutema, Marie Alexis, Vincent Chaplot, Lionel Cottenot, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), School of Agricultural, Earth and Environmental Sciences (SAEES), University of KwaZulu-Natal (UKZN), Laboratoire Sols et Environnement (LSE), Institut National de la Recherche Agronomique (INRA)-Université de Lorraine (UL), Milieux Environnementaux, Transferts et Interactions dans les hydrosystèmes et les Sols (METIS), École pratique des hautes études (EPHE)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Unité de recherche Science du Sol (USS), Institut National de la Recherche Agronomique (INRA), Agricultural Research Council-Institute for Agricultural Engineering, Institut National des Sciences de l’Univers (project EC2CO Destoc), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), École pratique des hautes études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), University of KwaZulu-Natal [Durban, Afrique du Sud] (UKZN), École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Unité de Science du Sol (Orléans) (URSols)

Subjects
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], Climate, [SDE.MCG]Environmental Sciences/Global Changes, Soil Science, chemistry.chemical_element, runoff, Carbon cycle, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, particule de carbone organique, changement global, carbone organique du sol, Global change, pratique culturale, global change, Earth-Surface Processes, changement climatique, climat, carbone dissous, 04 agricultural and veterinary sciences, Soil carbon, 15. Life on land, Particulates, travail du sol, ruissellement, 6. Clean water, Tillage, Agricultural practices, chemistry, 13. Climate action, Environmental chemistry, Soil water, 040103 agronomy & agriculture, Erosion, 0401 agriculture, forestry, and fisheries, Environmental science, Land degradation, Surface runoff, Agronomy and Crop Science, Carbon
Abstract

Although the impact of water erosion on soil carbon losses has been widely investigated, little is known about the relative contributions of dissolved, particulate and gaseous losses, a prerequisite for understanding the mechanisms of carbon (C) export from soils and designing mitigation procedures. The main objective of this study was to quantify the losses of dissolved organic and inorganic C (DOC, DIC), particulate organic C (POC) and soil CO2 from runoff microplots on tilled (T) and no-tilled (NT) soils. The study was performed in the Beauce region in central France under Luvisols using 45 and 80 mmh(-1) artificial rains. At 45 mm h(-1), T plots produced C erosion at an average of 1189.7 +/- 114.8 mg C m(-2) h(-1) with 76.9% of it being POC (915.0 +/- 100.0 mg C m(-2) h(-1)), 21.7% DOC (258.3.0 +/- 7.6 mg C m(-2)h(-1)), 1.4% (16.3 +/- 7.2 mg C m(-2)h(-1)), DIC and 0.01% CO2. NT decreased total soil C losses by 95% (from 0.8 to 0.038 g C m(-2)h(-1)) and soil C losses were as CO2 only. At 80 mm h(-1) NT surprisingly increased C erosion by 40% compared to T (from 39.4 to 55.3 g C m(2) h(-1)), with 95.5% of the C losses being POC vs 88.7% for T. These results on rainstorm-induced C fluxes from soils controlled by tillage are expected to be of future value: (1) for selecting appropriate land management that will mitigate against C losses from soils and improve soil carbon sequestration and; (2) to better understand the Global Carbon Cycle and further develop the existing models.

Published
2019

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