[GIS] Calculating volume using polygon instead of contour line in ArcGIS Desktop

arcgis-desktoparcmapdemlakesvolume

What I'm attempting to do is calculate the volume of a lake using a polygon I created by classifying an image for water. I then extracted the polygon from the classification process. What I'm left with is a polygon showing the surface area of the water. I have a DEM of the lake. How do I determine the amount of water this lake contains? I don't want to use a contour line if I dont have to because the heights vary at the edges of the lake.

This is with ArcGIS Desktop.

Best Answer

I assume that what you call “DEM of the lake” is DEM of lake bottom and surrounding area.

If this a case, it is a few steps procedure main ones being calculation of lake bank altitude and average lake depth.

  • Convert lake polygon to polyline, using feature to line tool

  • Set environment settings snap raster to DEM, cell size = one for DEM and convert polyline to raster using any numeric field, output to raster “BANK”. Use raster calculator expression:

    Con(~IsNull(”BANK”),”DEM”)

Output to raster “bankZ”.

  • Right click on bankZ, SOURCE and scroll to see mean value. This is average altitude of lake bank (meanZ).

  • Create numeric field in polygon and populate it by meanZ. Convert polygon to raster using that field, output “surfaceZ”.

  • Use raster calculator to calculate lake depth accounting for imperfections in DEM and lake delineation.

    Con(“surfaceZ”>”DEM”, “surfaceZ”-“DEM”,0)

Mean value of output is average lake depth. Now you can compute lake volume because lake area equal area of your polygon. Be careful with units

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