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Transfert de produits phytosanitaires par les écoulements latéraux en proche surface dans le Beaujolais de coteaux : suivi sur parcelle exploitée, expérimentation de traçage in situ et modélisation

Abstract : Subsurface lateral flow may stand for a risky pathway in several agro pedo climatic contexts: in this way, the aim of this thesis work is to improve our understanding of pesticide transfer and dynamics by this pathway. A farmed vine plot, located on a hillslope in the Nord Beaujolais, was instrumented with a trench, a Venturi flume and a shallow groundwater well network. The instrumentation was used during two farming years to continuously monitor pesticide transfers in both subsurface lateral flows and surface runoff at a fine temporal resolution. Lastly, an in situ tracing experiment was conducted and modeled. Hydrological results highlighted a threshold relationship between subsurface lateral flow volumes measured in the trench, the degree of lateral connectivity of the hillslope, rainfall amounts and initial soil water content. The dynamics of these transfers was very variable at the event scale, and in agreement with the physico chemical properties of the substances. Considering all subsurface lateral flow events, pesticides concentrations were described using a decreasing exponential function depending on the time interval between a given event and the last application of the considered pesticides, and their physico chemical properties. At the year scale, the seasonality of pesticide transfers seemed related with the seasonality of subsurface lateral flow and surface runoff. The tracing experiment highlighted two components in subsurface lateral flow: a matrix related one and a preferential related flow component. The preferential component implied short, highly concentrated and significant lateral fluxes. Matrix related component produced continuous and slightly concentrated fluxes over a long period, and was responsible for a bigger part of the total transfer than the preferential component. Links between substance properties and transfer components were highlighted
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https://tel.archives-ouvertes.fr/tel-01392743
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Submitted on : Friday, November 4, 2016 - 4:34:08 PM
Last modification on : Friday, October 23, 2020 - 4:41:19 PM
Long-term archiving on: : Sunday, February 5, 2017 - 2:38:22 PM

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  • HAL Id : tel-01392743, version 1
  • IRSTEA : PUB00051122

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Xavier Peyrard. Transfert de produits phytosanitaires par les écoulements latéraux en proche surface dans le Beaujolais de coteaux : suivi sur parcelle exploitée, expérimentation de traçage in situ et modélisation. Autre. Université de Lyon, 2016. Français. ⟨NNT : 2016LYSE1120⟩. ⟨tel-01392743⟩

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