Creating/Calculating 3D Subsurface Geology Volumes

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04-20-2017 05:45 PM
JamesAmato1
New Contributor

Hey All,

I have a question in regards to calculating subsurface geology volumes. Im working on trying to create 3D model of some beach ridges. For those that don’t know.. a beach ridge is a wave-swept or wave-deposited ridge running parallel to a shoreline. These packages of sediment have subsurface geometries that wedge-out at a ~5° dip lake-ward (please see photo links below).

I know how to calculate the surface volumes of the ridges, but am having trouble figuring out a way to create and calculate the volume of the wedges that pinch out below the surface. I don’t have any info on the extent or depth of the wedges (no borehole data), just trying to model the data off that ~5° dip lake-ward.

Is this a possibility in ArcMap/ArcScene or do I need the assistance of third party software like (http://www.aquaveo.com/software/ahgw-subsurface-analyst) or (http://www.leapfrog3d.com). I attempted to import a DEM into Sketchup but was having issues converting my DEM in ArcMap to the .dem / .ddf files that Sketchup allows. I also just tried to model things in Sketchup w/o the DEM and still had tremendous difficulty with the complex shapes involved.

Any feedback/insight would be greatly appreciated! Thanks

Orthophoto of study area: http://imgur.com/a/sHUha
ArcScene 3D photo w/ vertical exaggeration: http://imgur.com/a/kisGA
ArcMap polygon outlines: http://imgur.com/a/jARa6
Rough cross-section sketch of beach ridges: http://imgur.com/a/d7NcI

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NeilAyres
MVP Frequent Contributor

Do you have your ridge data as a tin?

You could create another tin by digitising a few points around the upper and lower sides, and with a bit of math, make it have a ~5deg slope.

Then use Surface Difference—Help | ArcGIS Desktop 

to get the volume.

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