Watershed Analysis with DEM's:
Newark (DE) East 7.5-Minute Quad

DEM's are useful for watershed delineation, surface flow analysis and simulations of water pollution processes:

Above: (1) Watershed basins calculated from the Newark East quad 30-meter DEM using the GRASS 4.1 r.watershed simulation utility, with vector streams (from TIGER);
(2) Terrain, by Watershed Basin created using Basin map for hue and Aspect for intensity.
(3) Water accumulation map generated from r.watershed showing calculated runoff volumes, with inferred stream channels in white (4X zoom of Northwest corner of quad).

GRASS info (Construction Engineering Research Labs, US Army Corps of Engineers)
EMGIS (U of Oklahoma): HYDROMOD and finite-element analysis modules in GRASS.
Ag Engineering Dept., Purdue; Integration of hydrologic models with GRASS.
SPATLAB home page
UD College of Agricultural Sciences home page