Spatial distribution of sediments and transfer properties in soils in a stormwater infiltration basin

Abstract : PurposeThe aim of our study was to characterise the heterogeneity of sediment distribution in a stormwater retention/infiltration basin (Pont de Cheviré, Nantes, France) and to determine the impact of this distribution on water transfer properties in the soil.Materials and methodsSoil water retention curves and saturated hydraulic conductivity (Ks) measurements were made at 11 points in the basin.Results and discussionA highly heterogeneous organic matter (OM) distribution ranging from 45 to 222 g kg-1 was observed in the surface layer (layer A), with a sediment thickness ranging from 5 to 26 cm. The sediment thickness of the underlying layer, primarily made up of sand (layer S), ranged from 7 to 32 g kg-1. We observed a significant influence of OM and fine mineral particles on the soil pore distribution and a negative correlation with the saturated hydraulic conductivity (values between 1.3e-5 and 7.2e-6 m s-1 in layer A and close to 3e-4 m s-1 in layer S).ConclusionsThis study allowed define the soil physical parameters that account for the clogging phenomenon in this infiltration basin. Nevertheless, this study raises questions as to the contribution of clay in the mineralogical sense on the one hand and OM dynamics on transfer properties and the clogging phenomenon on the other.