Influence of environmental factors on the wetting front depth: A case study in the Loess Plateau

• Results of field test performed for obtaining soil water contents and temperatures for one year are summarized.
• The maximum wetting front depth in loess soils taking account of environmental factors has been determined.
• The variation of water contents in loess soils in response to environmental factors is interpreted.
• Modelling of the flow behaviour in unsaturated loess using VADOSE/W is presented, analyzed and discussed.

Reliable information on the wetting front depth and variation of water contents within the zone of wetting is required for addressing geotechnical problems in loess deposits such as estimation of the collapse deformation and assessment of the slope stability. For this reason, a field test was conducted at a site in the Loess Plateau of China to obtain data on soil water contents and temperatures at different depths for a period of one year. The variation of water contents was interpreted from the influence of environmental factors and soil temperature, and used to determine the maximum wetting front depth in the loess soils in the study region. In addition, a commercial software, VADOSE/W, was used to simulate the flow behaviour in unsaturated loess taking account of the influence of environmental factors. A reasonable agreement was found between the results of field investigations and numerical simulations. The study results are useful as they provide valuable information about the wetting front depth and water content variation in unsaturated loess in response to environmental factors. The field investigations and numerical simulations summarized in this paper can serve as a reference for future studies on other soils.