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Master Thesis

Trajectoire d'un hydrosystème : le Guer amont sous-bassin du Léguer

Abstract : The aim of this memoir is to study the historical trajectory of landscape changes and hydrological connectivity in the Guer amont, a sub-watershed of the Leguer. Since the 19th century, this area of Brittany has experienced major changes in it’s agricultural landscape. From a vast bocage with high slopes and small farms, where a very family farming reign. To a landscape of open fields, with grouped plots of land often far from the farms. Thus, the Guer sub-basin knows in its change of landscape a whole agricultural revolution that’s taking place. Moreover, the landscape changes have fairly significant impacts on the hydro system. Indeed, the hydrological connectivity result of water flows dynamics must adapt to the changes of the landscape structure, particularly the levelling of hedges, which has many repercussions: hydro-sedimentary transfers, soil erosion, water pollution, eutrophication, loss of soil fertility, etc. In order to assess the impacts of hydrological connectivity and landscape changes, the first approach of the dissertation is to reconstruct landscape changes through the work of digitalisation. Consequently, the territory from the 1830s to the present can be reconstructed in the form of maps. Thus, we will be able to see the changes that have taken place in the landscape structure but also, in land use patterns throughout the 4 periods. The second approach is to model the hydrological connectivity in the territory using the multi-agent LASCAR model. The model is used to represent the trajectory of water flows and to identify the connected plots in the territory. The different hydrological connectivity, also carried out for the 4 periods, will allow us to understand the relationship between the organization of the landscape structure and the hydrological function in the study area. Also, the current modeling will identify connected and disconnected plots, as well as landscape elements that have a role in flow dynamics. The model will then be verified in the field, which will make it possible to validate the model and illustrate the various connectivity with photographs. Finally, the modeling will provide an analysis index, also represented in the form of a brochure, to help watershed managers identify parcels that require development.
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Master Thesis
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Submitted on : Thursday, November 5, 2020 - 12:15:20 PM
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  • HAL Id : dumas-02942640, version 1


Mathilde Guillemois. Trajectoire d'un hydrosystème : le Guer amont sous-bassin du Léguer. Géographie. 2020. ⟨dumas-02942640⟩



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