Exploring Effect of Mature Tree on Suction Distribution in a Natural Slope

Climate change altered variations in weather trends and rainfall fluctuations could trigger soil slope instability, causing landslides or debris flows. To mitigate such rainfall-induced slope failures, vegetated slopes are considered as an effective mechanism. For that reason, several studies have addressed the restraining of mechanical failures and advantages of evapotranspiration model in soil–plant-slope stability continuum. However, most of these investigations were examined on tree seedlings (1–2 m trunk height), which are relatively atypical and are insufficient to comprehend the vegetated slope mechanism. Besides, the variation of pore water pressure (directly related to slope stability) with different rainfall intensities are unclear. These critical measurements are required for modelling climate change-slope stability models and for practicing in long-term maintenance of man-made slopes. Therefore, this study attempted to investigate the temporal variation (suction distribution) of matured Ivy tree under different rainfall events (return periods equal to 20 years, 2 years and less than 2 years). The suction variations with different rainfall events were measured both vertically and horizontally below the root zones using jet fill tensiometers (± 1 kPa accuracy). The study provides evidence of suction distribution within the root zones, discussing the suction recovery after consecutive rainfall events and natural drying. Based on the observations, it was found that antecedent rainfall plays an effective role in suction recovery rates and changes in soil hydraulic conductivity.