My Pond's a Heap!

I was taking a look at some volumes a couple of days ago, and I thought I'd try an experiment.  Ihad a mound sitting on a pad and was wondering what the volume might be between one contour and another, say the 45.5 and 50 meter contours.  Here's the original mound.

Now, I've taken a slice through it between the contours I specified, so we get it looking like this.

Alright, I thought.  Let's see what happens when I calculate the volume of this slice using the standard surface volume tools, then compare that to the volume calculated by the Stage Stroage extension routine.  The Stage Storage etension is an add on for Civil 3D 2010 (and 2009) that computes basin volumes as a function of the elevations through the basin from bottom to top.  This mound slice is really just a basin that's turned upside down, so I thought it should work.

Here's what I got with the surface to surface volume tools,

Here's the volume from the Stage Storage routine.

That's pretty close.  Only a difference of 4.37 cubic meters if I use the conic method calculations for comparison.  The end area and the conic methods agree pretty closely within the Stage Storage (2441.28 for the end area method).

Creating the slice through the mound took a few steps, using the Stage Storage routine took a few clicks.  It's useful for determining volumes for different types of contoured shapes, not just your average pond.

If you haven't look at the add on functionality available for AutoCAD Civil 3D 2010, take the time to browse this site.  As whoever in your organization manages your subscriptions for access to the Autodesk Subscription website.  The latest content on the site are the Subscription Advantage Packs, available for a number of the Autodesk products.  I've found the Civil 3D 2010 se add ons to be great  extensions to the functionality of the product.

Check it out!
 

Comments

[Agustin]

Jeff,
How do you control the precision for the contour elevation interval for the Stage Storage Extension? Please advise.

Thank you

[Jeff Morrow]

The stage storage extension takes its contour data from the surface style, or, if you are using polylines, the polyline elevations. You also can add manual elevations and areas to the table. When using contours derived from a surface style, the routine uses integer values. When adding the values manually, the displayed precision is only one decimal place, regardless of how precise your entry is. The question is: is this just a display precision for the field in each case or is this the actual value used in the calculation? To be honest, I don't have an answer for you. I'm going to have to take a closer look and see what's happening behind the scenes. Stay tuned!