Before the construction project, it is necessary to investigate the hydrological conditions of territory. For this purpose some hydrophysical indicators of the soil should be measured. Among the most important indicators is the water-retention capacity. It is convenient to use a physically justified model to research sorption-desorption properties of soil with respect to moisture. The authors have investigated the mathematical model, which was developed to describe the hysteresis of water-retention capacity. The computer program “HYSTERESIS” was been used to implement this research. Three computational experiments were carried out with the use of this program. The results allow improving the accuracy of calculating the dynamics of soil moisture. The results of the research could be applied to the agricultural research, hydrological conditions investigations and other area of knowledge.