EGU21-7355, updated on 22 Apr 2021
https://doi.org/10.5194/egusphere-egu21-7355
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Coupling large and small ring infiltration experiments for investigating preferential flow

Laurent Lassabatere1, Simone Di Prima2, Paola Concialdi3, Majdi Abou Najm4, Ryan D. Stewart5, Vincenzo Bagarello3, Massimo Iovino3, Mirko Castellini6, Jesús Fernández-Gálvez7, Joseph Pollacco8, Deniz Yilmaz9, and Rafael Angulo-Jaramillo1
Laurent Lassabatere et al.
  • 1ENTPE, University of Lyon LEHNA UMR 5023 CNRS ENTPE UCBL, Vaulx en Velin, France (laurent.lassabatere@entpe.fr)
  • 2Agricultural Department, University of Sassari, Viale Italia, 39, 07100 Sassari, Italy
  • 3Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy
  • 4Department of Land, Air and Water Resources, University of California, Davis, CA 95616, United States
  • 5School of Plant and Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, United State.
  • 6Council for Agricultural Research and Economics-Research Center for Agriculture and Environment (CREA-AA)
  • 7Department of Regional Geographic Analysis and Physical Geography, University of Granada, Spain
  • 8Manaaki Whenua – Landcare Research, Lincoln 7640, New Zealand
  • 9Civil Engineering Department, Engineering Faculty, Munzur University, Tunceli, Turkey

Preferential flow is more the rule than the exception. Water infiltration is often led by preferential flow due to macropores, specific soil structures (e.g., aggregates, macropore networks), or lithological heterogeneity (occurrence of materials with contrasting hydraulic properties). Water infiltration in soils prone to preferential flow strongly depends on soil features below the soil surface, but also the initiation of water infiltration at the surface. When the macropore networks are not dense, with only a few macropores intercepting the soil surface, water infiltration experiments with ring size in the order of 10-15 cm diameter may overlook sampling macropore networks during some infiltration runs, minimizing the effect of macropore flow on the bulk water infiltration at the plot scale.

In this study, we investigated the effect of ring size on water infiltration into soils prone to preferential flow. We used two ring sizes: small (15 cm in diameter) and large (50 cm in diameter). By doing so, we hypothesized that the large rings, sampling a more representative soil volume, will maximize the probability to intercept and activate a macropore network. In contrast, the small rings may activate the macropore network only occasionally, with other infiltration runs mainly sampling the soil matrix. Thus, the small rings are expected to provide more variable results. On the other hand, the large rings are expected to provide more homogeneous results in line with the soil's bulk infiltration capability, including all pore networks at the plot scale.

Three different sites were sampled with varying types of preferential flow (macropore-induced versus lithological heterogeneity induced). The experimental plan included inserting large rings at several places in the experimental sites with a dozen small rings nearby to sample the same soil. All the rings were submitted to a similar positive constant water pressure head at the soil surface. The cumulative infiltrations were then monitored and treated with BEST algorithms to get the efficient hydraulic parameters. Note that the cumulative infiltration could not be compared directly since lateral water fluxes varied in extent and geometry between the different ring sizes. The impacts of the ring size on the magnitude of cumulative infiltration and related estimated hydraulic parameters were discussed. Our results demonstrated the impact of ring size but also the dependency of such effect on the site and the type of flow.

Our results contribute to understanding preferential flow in heterogeneous soils and the complexity of its measure using regular water infiltration devices and protocols.

How to cite: Lassabatere, L., Di Prima, S., Concialdi, P., Abou Najm, M., Stewart, R. D., Bagarello, V., Iovino, M., Castellini, M., Fernández-Gálvez, J., Pollacco, J., Yilmaz, D., and Angulo-Jaramillo, R.: Coupling large and small ring infiltration experiments for investigating preferential flow, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7355, https://doi.org/10.5194/egusphere-egu21-7355, 2021.

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