Environmental impact assessment (EIA) is a key tool for both environmental and land management. It identifies potential adverse and unintended consequences of the projects on land use and the environment and derives possible mitigation measures to address these impacts. Calculating the volume and severity of impacts is complex and often relies on selections and simplifications. Moreover, calculating impacts associated with nomadic-pastoral (dynamic) land use is still an unresolved methodological problem. A full understanding of the patterns of dynamic land use in nomadic pastoralism is still lacking. Consequently, EIAs are currently able to predict the negative impacts associated with dynamic land use insufficiently. This article addresses this lacuna by modeling the spatial occupation of grazing land using a statistical modeling technique of structural equation modeling (SEM) and the R package lavaan for SEM, in order to explain the behavior of dynamic land use for EIA. Based on the concepts of the production of space and pastoral spatiality, we specified and tested a model of spatial occupation of grazing areas hypothesizing interrelationships between factors influencing the pastoral space using empirical data from two different ecological zones in Mongolia. The findings suggest that grazing areas, herd mobility, and herd size and composition have direct positive effects on each other. Compared to broad-scale pastoral movements, the herd size and composition significantly affect the size of grazing areas and the extent of fine-scale herding mobility. Herders occupy more pastoral space and increase their daily herding movements at their campsites when the population of livestock increases. By contrast, the herd size and composition do not considerably affect the herders’ decision to migrate for extensive grazing between their seasonal campsites. Likewise, the scale of grazing areas and fine-scale pastoral mobility do not affect significantly the broad-scale herding mobility between campsites. The broad-scale herding mobility is relatively independent of the fine-scale mobility; however, they covary. This is the first study to analyze and quantify the effects of grazing areas, herding mobility, and herd size and composition in the same study. EIA impact prediction should consider grazing areas as a dynamic space that is influenced by grazing orbits, fine and broad-scale herding movements including otor, livestock species, the number of animals as well as households at campsites.