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Examining the mid to longāterm variability in saturated hydraulic conductivity of sandy soils and its influencing factors under constant head test in the laboratory
Abstract
Saturated hydraulic conductivity (Ks) is a crucial parameter that influences water flow in saturated soils, with applications in various fields such as surface water runoff, soil erosion, drainage, and solute transport. However, accurate determination of Ks is challenging due to temporal and spatial uncertainties. This study addresses the knowledge gap regarding the longāterm behavior of Ks in sandy soils with less than 10% fine particles. The research investigates the changes in Ks over a long period of constant head tests and examines the factors influencing its variation. Two sandy samples were tested using a hydraulic conductivity cell, and the hydraulic head and discharge were recorded for over 50 days. The results show a general decline in Ks throughout the test, except for brief periods of increase. At the end of both tests, there are noticeable reductions in the saturated hydraulic conductivities of the samples, with one sample being 96% and the other sample 91% less than the maximum recorded saturated hydraulic conductivity during the tests. Furthermore, the relationship between flow rate and hydraulic head gradient does not follow the expected linear correlation from Darcy's law, highlighting the complex nature of sandy soil saturated hydraulic conductivity. The investigation of soil properties in three different sections of the samples before and after the tests revealed a decrease in the percentage of fine particles and a shift in specific gravity from the bottom to the top of the sample, suggesting particle migration along the flow direction. Factors such as clogging by fine particles and pore pressure variation contribute to the changes in Ks. The findings of this research show the importance of considering changes of saturated hydraulic conductivity during constantāhead laboratory tests. Therefore, this study provides evidence for the requirement to further assess the laboratory methods for measurement of the saturated hydraulic conductivity in sandy soil mixtures.
Type
Journal Article
Type of thesis
Series
Citation
Nikghalb Ashouri, S., Pittari, A., Moon, V., & Shokri, A. (2024). Examining the mid to longāterm variability in saturated hydraulic conductivity of sandy soils and its influencing factors under constant head test in the laboratory. Water Resources Research, 60(10). https://doi.org/10.1029/2023wr036164
Date
2024
Publisher
American Geophysical Union (AGU)
Degree
Supervisors
Rights
Attribution 4.0 International. This is an authorās accepted version of an open access article published in the Water Resources Research. Ā© 2024 American Geophysical Union (AGU).