Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips – Part 1: nonuniform infiltration and soil water redistribution

Effets d'une nappe peu profonde sur le transport d'eau, sédiments et pesticides dans une bande enherbée. Part A. infiltration non-uniforme et redistribution de l'eau dans le sol

R. Munoz Carpena (1) , Claire Lauvernet (2) , Nadia Carluer (2)

1 UF - University of Florida [Gainesville]
2 RiverLy - Fonctionnement des hydrosystèmes

Vegetation buffers like vegetative filter strips (VFS) are often used to protect water bodies from surface runoff pollution from disturbed areas. Their typical placement in bottomland often results in the presence of a seasonal shallow water table (WT) that can decrease soil infiltration and increase surface pollutant transport during a rainfall/runoff event. Simple and robust components of hydrological models are needed to analyse the impacts of WT in the landscape. To simulate VFS infiltration under realistic rainfall conditions with WT, we propose a generic infiltration solution (Shallow Water table INfiltration algorithm: SWINGO) based on a combination of approaches by Salvucci and Entekhabi (1995) and Chu (1997) with new integral formulae to calculate singular times (time of ponding, shift time, and time to soil profile saturation). The algorithm was tested successfully on 5 distinct soils both against Richards’s numerical solution and experimental data in terms of infiltration and soil moisture redistribution predictions, and applied to study the combined effects of varying WT depth, soil type, and rainfall intensity and duration. The results show the robustness of the algorithm and its ability to handle various soil hydraulic functions, and initial non-ponding conditions under unsteady rainfall. The effect of a WT on infiltration under ponded conditions was found effectively decoupled from surface infiltration/excess runoff processes for depths larger than 1.2 to 2 m, shallower for fine soils and shorter events. For non-ponded initial conditions, the influence of WT depth also varies with rainfall intensity. Also, we observed that soils with a marked air entry (bubbling pressure) exhibit a distinct behaviour with WT near the surface. The features and good performance of SWINGO support its coupling with an existing VFS model in the companion paper, where the potential effects of seasonal or permanent WTs on VFS pollutant transport and control are studied.

Mots clés: pesticides; grass-covered buffer zone

Mots clés: DISPOSITIF ENHERBE; PESTICIDE; SEDIMENT; INFILTRATION

Domaines: Sciences de l'environnement; Hydrologie

R. Munoz Carpena, Claire Lauvernet, Nadia Carluer. Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips – Part 1: nonuniform infiltration and soil water redistribution. Hydrology and Earth System Sciences, 2018, 22 (1), pp.53-70. ⟨10.5194/hess-22-53-2018⟩. ⟨hal-01738123⟩