Occupation des sols et gestion de l'eau : modélisation prospective en paysage agricole fragmenté (Application au SAGE du Blavet)

Abstract : If major land use / landcover changes (deforestation, urbanization...) have induced important environmental damages at the global scale, subtle changes that occur at the local scale may also have dramatic consequences. For example, land cover and landscape feature changes in the agricultural patchy landscape of Brittany (France) over the last 50 years have caused significant water quality degradation. Since the new European water policy (2000/60/EC Directive), water managers must restore a “good ecological state” of water resources for 2015. To be more efficient and provide sustainability, water management policies have to be implemented at a local scale (i.e. hedgerow or field scale), where water acquires its physical and chemical properties, but they must also adopt a long term vision, i.e. considering possible future land use and landcover changes. The production of prospective scenarios of landcover and landscape feature changes at a fine scale may considerably help water managers to realize more effective water policy controls.
The aim of this work is to implement a generic methodology to build spatialized prospective scenarios. Based on the methodology of scenarios, its implementation is to provide a spatial rendering using acquaintances coming from complex system modelling. Intended for helping the elaboration of the Water Management Plan of the Blavet watershed (2000 km²), its application is made on three smaller watersheds representative of the Blavet landscape diversity. This generic methodology is organized in four phases. The first phase is to build the “base” of the scenarios. The second consists in making adapted scenarios to explore possible future states of the study sites. The third is to spatialize the prospective scenarios. Considering the different scenarios, differentiated methods were used: a modelling platform (L1) that produces dynamic and spatially explicit simulations is used and optimized for exploratory scenarios; GIS have been employed for normative scenarios. Phase four evaluates the spatialized prospective scenarios: their impacts on water resources and their contribution to water managers and local decision-makers.
The exploratory scenarios have quantified and localized the possible influence on landcover changes based on the new policy reform of the European Common Agricultural Policy to be implemented in 2006 and of the current trend in farm enlargement in the region, and also the influence of fields' structure changes on water fluxes. Normative scenarios have identified future stakes of water management. Localization of at-risk areas towards water resources and identification of stakeholders contribute to consider spatialized prospective scenarios as powerful tools to help decision-makers to manage water resources efficiently and sustainability.
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https://tel.archives-ouvertes.fr/tel-00389835
Contributor : Thomas Houet <>
Submitted on : Friday, May 29, 2009 - 5:39:19 PM
Last modification on : Tuesday, May 7, 2019 - 6:30:08 PM
Long-term archiving on : Thursday, June 10, 2010 - 9:59:22 PM

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  • HAL Id : tel-00389835, version 1

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Thomas Houet. Occupation des sols et gestion de l'eau : modélisation prospective en paysage agricole fragmenté (Application au SAGE du Blavet). Géographie. Université Rennes 2, 2006. Français. ⟨tel-00389835⟩

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