Common uses of DEMs

Extracting terrain parameters,Modeling water flow or mass movement (for example avalanches and landslides),Creation of relief maps,Rendering of 3D visualizations,3d flight planning,Creation of physical models (including raised-relief maps),Rectification of aerial photography or satellite imagery, Reduction (terrain correction) of gravity measurements (gravimetry, physical geodesy), Terrain analyses in geomorphology and physical geography, geographic information system(GIS), Engineering and infrastructure design, Global positioning systems (GPS), Line-of-sight analysis, Base mapping, Flight simulation, Precision farming and forestry, surface analysis, Intelligent transportation systems (ITS).

Reference: Wikipedia