Interplay between Fingering Instabilities and Initial Soil Moisture in Solute Transport through the Vadose Zone
Name
water-12-00917-v2.pdf
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45.93 MB
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Author(s)
Cueto-Felgueroso, Luis
Suarez-Navarro, María José
Fu, Xiaojing
Juanes, Ruben
Date Issued
March 2020
Journal
Water
Publisher
Multidisciplinary Digital Publishing Institute
Citation
Cueto-Felgueroso, Luis et al. "Interplay between Fingering Instabilities and Initial Soil Moisture in Solute Transport through the Vadose Zone." Water 12, 3 (March 2020): 917 © 2020 The Authors
Version
Final published version
Abstract
Modeling water flow and solute transport in the vadose zone is essential to understanding the fate of soil pollutants and their travel times towards groundwater bodies. It also helps design better irrigation strategies to control solute concentrations and fluxes in semiarid and arid regions. Heterogeneity, soil texture and wetting front instabilities determine the flow patterns and solute transport mechanisms in dry soils. When water is already present in the soil, the flow of an infiltration pulse depends on the spatial distribution of soil water and on its mobility. We present numerical simulations of passive solute transport during unstable infiltration of water into sandy soils that are prone to wetting front instability. We study the impact of the initial soil state, in terms of spatial distribution of water content, on the infiltration of a solute-rich water pulse. We generate random fields of initial moisture content with spatial structure, through multigaussian fields with prescribed correlation lengths. We characterize the patterns of water flow and solute transport, as well as the mass fluxes through the soil column. Our results indicate a strong interplay between preferential flow and channeling due to fingering and the spatial distribution of soil water at the beginning of infiltration. Fingering and initial water saturation fields have a strong effect on solute diffusion and dilution into the ambient water during infiltration, suggesting an effective separation between mobile and inmobile transport domains that are controlled by the preferential flow paths due to fingering.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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Creative Commons Attribution
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DOI of Published Version
https://doi.org/10.3390/w12030917
