This book offers a comprehensive examination of Digital Elevation Models (DEMs) and their applications in environmental analysis, combining foundational concepts with practical methodologies. It introduces key principles of geoprocessing and GIS, provides an in-depth overview of global DEMs and their limitations, and systematically explores techniques for terrain characterization, flow direction and drainage network extraction, basin delineation, flow path analysis, and inundation mapping for applications such as reservoir planning. Three dedicated chapters on topographic indices bridge theory and practice in hydrology, ecology, and wind exposure studies. The final chapter addresses the critical role of error and uncertainty in DEM processing, emphasizing quality assessment in hydrological modeling. Richly illustrated and grounded in current research, this resource equips students and professionals to effectively integrate DEMs into environmental studies.