Water storage is one of the important indicators for ecological assessment of terrace. The water storage benefit of terrace may differ with the terrace type, rainfall characteristics, soil type, terrain, and others in many regions. Existing case studies use runoff plot data and model simulation to estimate the water storage benefit of terrace; yet, a consistent estimation framework and methodology have not been developed. Based on the soil reservoir calculation model and infiltration model, we explore the prediction methods of soil water distribution in saturation-excess runoff and infiltration-excess runoff, respectively. Moreover, we analyze the two-dimensional infiltration of soil profiles at different field and ridge boundaries. Thus, we proposed the estimation method of soil water storage capacity. On this basis, we construct the scenario of soil water movement under single runoff generation mode or two runoff generation modes under four types of rainfall patterns, including pre-peak rainfall, uniform rainfall, post-peak rainfall, and stepped rainfall patterns. The occurrence time and critical value of different runoff patterns were explored in different scenarios. The findings would provide a reference for the estimation of water storage benefits under different rain patterns.