Aller au contenu
Aller au menu
Aller à la recherche
Aller au pied de page

Filtration function of an urban structure – Consequence on the formation of an anthroposol (FAFF)

Filtration function of an urban structure – Consequence on the formation of an anthroposol (FAFF)

Summary
Urban planning can have irreversible effects on soils because it triggers the reduction of areas occupied by natural soils and thus their role with regards the infiltration of water and groundwater recharge. Urban development means the extension of impervious surfaces and the increase in water runoff; which requires the development of best management techniques in addition to usual sewer systems. Among these techniques, infiltration basins constitute a good compromise and help restoring the water cycle. But these techniques have two shortcomings: i) the accumulation of pollutants at surface leads to the formation of a sedimentary layer that can combine with the underlying geological substrate to form a new polluted soil; ii) the release of pollutants from the sedimentary layer may constitute a risk regarding groundwater quality. The filtering function, that allows the removal of pollutant from water before it reaches the groundwater, is one of the key roles played by soils and must be investigated for these new types of soils. This project aims to improve the knowledge on the formation of this type of new soils, referred to as anthroposol, and to characterize their filtering function.

This report presents the a large and original database related to a specific infiltration basin located in an industrial area, for which deep investigations have been carried out, in combination with higher level data obtained for 18 other infiltration basins. All the infiltration basins were located on the outwash plain of the East Lyon basin. The main results show i) the role played by the heterogeneity of soil on the distribution of pollutants; ii) a common pattern characteristic of urban surface sediments regardless the type of human activity in the watershed; iii) the adequacy of geophysical methods (GPR, ERT, RMP) for the description of soil heterogeneity and the understanding of flow heterogeneity ; iv) the adequacy of modeling unsaturated flow and pollutant transfer to understand the in situ observations. Finally, this work suggests some recommendations for stakeholders. For example, the choice of a specific site for water infiltration may combine the assessment of the infiltration capability with geochemical characteristics and the heterogeneity with regards soil texture and structure.

haut de page

 

Contact
CNRS - Laboratoire d’Écologie des Hydrosystèmes Naturels et Anthropisés (Thierry Winiarski)

haut de page