Abstract: Based on the water balance principle and the expanding Dupuit assumption, a model is developed to determine the saturated depth over the barrier in landfill cover system. Using this model, the variation of the saturated depth over time is analyzed under four different rainfall patterns, which include uniform, previous peak, center peak and post-peak patterns. Then, the effects of rainfall pattern, hydraulic conductivity of drainage layer, horizontal drainage distance and drainage slope on the maximum saturated depth are studied. The calculated results show that the saturated depth grows fastest under the previous peak pattern and the most slowly under the post-peak pattern, and falls somewhere between these two extremes for the uniform and center peak patterns. The maximum saturated depth significantly decreases when the hydraulic conductivity gradually increases in some range. However, the maximum saturated depth quickly increases with the increase of horizontal drainage distance.