Many processes in a developing catchment can only be fully understood if the spatial heterogeneity is adequately described. Process-based modeling allows reproducing specific key structural elements of catchments. Constructed catchments are ideal test objects because of the well-known spatial conditions. In our study, we (i) modeled the entire process chain of catchment construction, (ii) established a consistent sediment mass/volume balance between the excavated outcrop and the generated catchment model, and (iii) provided consistent three-dimensional distributions of texture and bulk density for deriving soil hydraulic properties. Data are from the 6 ha Hühnerwasser catchment (Chicken Creek, Lower Lusatia, Germany), which was constructed from overburden sediments in an open-cast lignite mine. Uncertainty about the parent material origin was captured in a multiscenario approach based on a geological model of the outcrop site and the simulation of excavation procedures. Generated distributions are incorporated in a gridded three-dimensional volume model (GOCAD), and results were evaluated by semivariogram analysis and by quantifying point-to-point deviations. Filling and compaction are modeled based on three-dimensional volume analysis and mass balances of dumped sediments. Heterogeneities reflect both the batch-wise sediment variation and the succession of excavated geological units. The scale of the generated spatial models can be adjusted for three-dimensional hydrological catchment modeling while three-dimensional sediment mass balances can be used for analyzing soil and ecosystem development processes.