r.earthworks: a GRASS tool for terrain modeling

r.earthworks is a tool for modeling terrain in GRASS, a free and open source geospatial processing engine ( GRASS Development Team et al., 2025).This tool -inspired by earthworking operations that reshape the earth's surface -transforms existing terrain rasters.Earthworks are constructed by excavating or embanking soil and rock.In cut operations, earth is removed, dug out by machines such as excavators or pushed away by dozers.In fill operations, earth is added, deposited by machines such as loaders or pushed in place by dozers.r.earthworks models topographic change as cut or fill operations that add to or subtract from a topographic surface.Topographic change can be calculated relative to a vertical datum to model features at a given elevation or relative to the topographic surface to model features that follow the terrain.While inspired by earthworking processes, r.earthworks can be used to model natural as well as constructed landforms.Applications include procedurally generating terrain (Figure 1), designing earthworks (Figure 2), modeling landforms (Figure 3), simulating processes such as dam or levee breaches, reconstructing historic landscapes, and removing anomalies.As part of the GRASS ecosystem, r.earthworks can easily be used in conjunction with other tools for geomorphometry (Jasiewicz & Stepinski, 2013), hydrological modeling (Mitášová et al., 2004), erosion modeling (Harmon et al., 2019), and temporal analysis (Gebbert & Pebesma, 2017) in Python scripts and Jupyter notebooks (Haedrich et al., 2023).Figure 2: Levee improvements and ridge restoration modeled with r.earthworks