Effects of dynamic changes of desiccation cracks on preferential flow: experimental investigation and numerical modeling

Journal Article (2023)
Author(s)

Yi Luo (China University of Geosciences, TU Delft - Water Resources)

Jiaming Zhang (China University of Geosciences)

Zhi Zhou (Hubei University Of Economics)

Juan Pablo Aguilar Lopez (TU Delft - Hydraulic Structures and Flood Risk)

Roberto Greco (Università degli Studi della Campania “Luigi Vanvitelli”)

Thom Bogaard (TU Delft - Water Resources)

Research Group
Hydraulic Structures and Flood Risk
Copyright
© 2023 Y. Luo, Jiaming Zhang, Zhi Zhou, J.P. Aguilar Lopez, Roberto Greco, T.A. Bogaard
DOI related publication
https://doi.org/10.5194/hess-27-783-2023
More Info
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Publication Year
2023
Language
English
Copyright
© 2023 Y. Luo, Jiaming Zhang, Zhi Zhou, J.P. Aguilar Lopez, Roberto Greco, T.A. Bogaard
Research Group
Hydraulic Structures and Flood Risk
Issue number
3
Volume number
27
Pages (from-to)
783–808
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Abstract

Preferential flow induced by desiccation cracks (PF-DC) has been proven to be an important hydrological effect that could cause various geotechnical engineering and ecological environment problems. Investigation on the PF-DC remains a great challenge due to the soil shrinking–swelling behavior. This work presents an experimental and numerical study of the PF-DC considering the dynamic changes of desiccation cracks. A soil column test was conducted under wetting–drying cycles to investigate the dynamic changes of desiccation cracks and their hydrological response. The ratios between the crack area and soil matrix area (crack ratio), crack aperture and depth were measured. The soil water content, matrix suction and water drainage were monitored. A new dynamic dual-permeability preferential flow model (DPMDy) was developed, which includes physically consistent functions in describing the variation of both porosity and hydraulic conductivity in crack and matrix domains. Its performance was compared to the single-domain model (SDM) and rigid dual-permeability model (DPM) with fixed crack ratio and hydraulic conductivity. The experimental results showed that the maximum crack ratio and aperture decreased when the evaporation intensity was excessively raised. The self-closure phenomenon of cracks and increased surficial water content was observed during low-evaporation periods. The simulation results showed that the matrix evaporation modeled by the DPMDy is lower than that of the SDM and DPM, but its crack evaporation is the highest. Compared to the DPM, the DPMDy simulated a faster pressure head building-up process in the crack domain and higher water exchange rates from the crack to the matrix domain during rainfall. Using a fixed crack ratio in the DPM, whether it is the maximum or the average value from the experiment data, will overestimate the infiltration fluxes of PF-DC but underestimate its contribution to the matrix domain. In conclusion, the DPMDy better described the underlying physics involving crack evolution and hydrological response with respect to the SDM and DPM. Further improvement of the DPMDy should focus on the hysteresis effect of the soil water retention curve and soil deformation during wetting–drying cycles.