Volume Computation

Icon on map window toolbar if you have a DEM map or a DEM associated with the image map.

Computes the volume above the a specified elevation level, the volume below, and the the total volume. It is intended to be used with a difference DEM, such as before and after DEMs of Mt. St. Helens, before and after DEMs of the Slumgullion landslide, or coastal lidar DEMs taken at different times to track erosion/deposition.  You could also use it to compute volume for a body of water.  It may or may not be applicable to other DEMs.

Outline the region specified, either with stream or point mode digitizing.

Use an area shape file, double click on a record, and compute the volume of that area.

For each point in the DEM inside the region, the program computes the elevation difference from the specified elevation level.  It multiplies this by the area represented by each point (average x and average y dimensions, which are either the UTM values or the converted values in meters for arc second DEMs).  It then sums all the values for all the points inside the region.

Last revision 12/14/20179