You can calculate the volume or area between contours either manually or by using a script to automate the process in Surfer.
- Click Grids| Calculate | Volume.
- In the Grid Volume dialog, click Browse.
- In the Open Grid dialog, select your grid file and click Open.
- Set the grid file as the Upper Surface| Grid File and the Z level of the first contour as the Lower Surface (Constant Z = ).
- Click OK.
- Record the Volumes | Cut & Fill Volumes | Positive Volume [Cut] value or Areas | Planar Areas | Positive Planar Area [cut] value for areas from the report.
- Repeat steps 1 - 6, generating a second report with the same grid file as the Upper Surface and the Z level of the second contour as the Lower Surface.
- Subtract the second value from the first value to get the volume or area between the two contours.
- The contarea.bas script calculates the area between evenly spaced contour levels automatically. Download the script, open the BAS file in Scripter (comes with Surfer), and go to Script | Run. Follow the prompts to generate the report.
Updated October 31, 2017.