Quantifying hydro-sedimentary transfers in a lowland tile-drained agricultural catchment

Thomas Grangeon (1) , Valeria Ceriani (2, 3) , Olivier Evrard (2, 3) , Aurélie Grison (4) , Rosalie Vandromme (1) , Arthur Gaillot (5, 1) , Olivier Cerdan (1) , Sébastien Salvador-Blanes (5)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
3 GEDI - Géochimie Des Impacts
4 Syndicat Mixte du Bassin versant de la Bonnée
5 GéHCO EA6293 - GéoHydrosystèmes COntinentaux

Soil erosion, runoff and sediment connectivity are strongly impacted by anthropogenic features in lowland agricultural catchments. Among these landscape features, the role played by tile drainage on water and sediment transfers and hillslope-to-river connectivity in drained catchments remains poorly understood. This study quantified water and sediment transfers in a tile drained catchment of central France by combining high frequency rainfall, discharge and sediment concentration measurements at the outlet of a set of 10 tile drained plots (34 ha) and at the medium-sized (120 km2) catchment scale. Over the monitoring period, including a dry and a wet year compared to average conditions (one year with 112% of the mean annual rainfall and one year with 64% of the mean annual rainfall), 36 rainfall-flood events were recorded and analyzed. The high frequency analysis of water and sediment transfers in tile-drained plots showed a high seasonal variability and the occurrence of two transfer pathways in the soil column including the slow drainage of saturated soils and the occurrence of preferential flow pathways through the soil column. Indeed, 13 of the 36 recorded flood events showed hydrographs with two components, reflecting these two pathways: slow transfers in the soil columns and fast transfers through soil macropores and/or cracks. Indeed, at the beginning of the flood event, a high-magnitude peak overlaid on the hydrograph. On average, this fast peak contributed 15% of the water and sediment fluxes. The sediment dynamics in tile drains was suggested to depend on sediment storage and exhaustion processes occurring in the tile drain network.

Mots clés: Soil erosion; Suspended sediment transfers; Tile drainage

Domaines: Sciences de l'environnement; Interfaces continentales, environnement; Géomorphologie; Hydrologie; Science des sols

Thomas Grangeon, Valeria Ceriani, Olivier Evrard, Aurélie Grison, Rosalie Vandromme, et al.. Quantifying hydro-sedimentary transfers in a lowland tile-drained agricultural catchment. CATENA, 2021, 198, pp.105033. ⟨10.1016/j.catena.2020.105033⟩. ⟨cea-03011226⟩