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Author: search.filters.author.Feng, SongHas files: No

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    The influence of root-crack dynamics on soil water infiltration across seasonal variations
    (2025-12-01)
    Yuliana, Yuliana
    ;
    Apriyono, Arwan
    ;
    Munirwan, Reza Pahlevi
    ;
    Feng, Song
    ;
    Kamchoom, Viroon
    Soil infiltration plays a vital role in the hydrological cycle, impacting water absorption and availability for crops. Accurate infiltration measurements are crucial for improving water management in agricultural systems. This study observed the interaction of root growth and crack to the infiltration rate with influence of wetting drying conditions. Over an 18-month period, a double-ring infiltrometer test was applied to directly assess infiltration rates in both bare and vegetated zones. A minirhizotron camera was used to capture the root growth and decay defined as Root Area Ratio (RAR) and crack defines as crack intensity factor (CIF). The findings reveal that root growth peaked at 6.3 % during the first cycle but declined to 4.5 % in the second dry summer due to water stress and root decay. Vegetated zone also experienced lower CIF compared to bare zone. Infiltration rates increased significantly during dry periods, with the bare zone reaching a final rate of 1.63 × 10⁻⁶ m/s and vegetated zones showing up to an 8-fold increase in the second cycle. These findings underscore the critical role of root dynamics and soil cracking in regulating water infiltration. For agricultural systems, understanding these processes is essential for developing effective soil management and irrigation strategies that improve infiltration, enhance soil stability, and optimize crop productivity.
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    Semi-analytical solutions for pore-water pressure distributions and slope stability in an infinite multi-layered vegetated slope considering highly-nonlinear hydraulic properties of soil
    (2025-10-01)
    Feng, Song
    ;
    Huang, Ruhong
    ;
    Li, Guangyao
    ;
    Zhan, Liangtong
    ;
    Kamchoom, Viroon
    Accurately depicting the highly nonlinear hydraulic properties of soil is critical for predicting pore-water pressure distributions and evaluating the stability of vegetated slopes. Accordingly, semi-analytical solutions are proposed for calculating pore-water pressure distributions and slope stability in an infinite multi-layered slope considering both hydrological and mechanical effects of vegetation. The solutions have the advantage of depicting the highly nonlinear hydraulic properties of soil, both with and without roots, using a multi-exponential function. After verifying the solutions, parametric studies are conducted to investigate influential factors on pore-water pressure distributions, including root architecture, root volume ratio, root depth and the combination of different soil layers in landfill cover. It is found that compared to the multi-exponential function, the single-exponential function commonly used in published solutions significantly underestimates negative pore-water pressure induced by root water uptake by up to 65 kPa under drying conditions, because it fails to depict soil hydraulic properties accurately. When root reduces the hydraulic conductivity of unsaturated soil, larger negative pore-water pressure induced by root water uptake within root zone could be observed under drying conditions, while the trend reverses under wetting conditions. The effects of root architecture and root-induced changes in the hydraulic conductivity of unsaturated soil on pore-water pressure distributions become more significant as the root volume ratio increases. Under drying conditions, root water uptake induces the largest negative pore-water pressure near the ground surface in the three-layer landfill cover, compared with the cover with capillary barrier effects and single-layer cover. The derived solutions can be used to guide engineering practices of vegetated slope and landfill cover.