“only for historical reference”

‘Think “CSI: Gulf Coast” with surveyors taking the place of coroners and investigators, plumb bobs, GPS units and spray paint instead of DNA kits, rubber gloves and toe tags.’

The USGS Digital Elevation Model (DEM) data files are digital representations of cartographic information in a raster form. DEMs consist of a sampled array of elevations for a number of ground positions at regularly spaced intervals.

Map of real-time streamflow compared to historical streamflow for the day of the year (United States)