Volume Calculations

[roscopeco2000]

Hello I need some help i createded some 3D terrain using a 3D DWG file, and added a floor and offset to show the effects of flooding. I am now being asked to calculate the volume of water above the ground level. I am at complete lose, anyone have an idea how to do this?

[ToanDN]

Create a void the same shape as the terrain, use it to subtract the water to get the true volume.

[Stanis-74]

copy to clipboard your terrain, paste it to the same place and correct new volume as looks with water (or repeat the flooding volume).

now you need compare two volumes (or find in properties the value you need)

[roscopeco2000]

Sorry how do i "correct new volume as looks with water"?

[roscopeco2000]

So how i would get the terrain into a family part to give me the necessary information to create a void? 

[Stanis-74]

in redactor you can add dots of your terrian. so, you need to add dots with elevation wich equals elevation of water top.

[roscopeco2000]

I think i understand what you mean but in properties it only reports area not volume see below....

[ToanDN]

Oh I misunderstood. I thought you created solid, not topography. I will look at it again.

[ToanDN · Accepted solution]

Create a graded region from the existing topo, choose perimeter only, then add point around the water to define the flat water body. See you can get Fill volume from that.

[roscopeco2000]

Thanks but when i got round my red floor area set at 44800 i get the following do i just deleted the points around the outside??

[ToanDN · Accepted solution]

You don't have to.  By the way, try create a graded region one more time but with create an identical copy of the existing topography, then delete the point inside the lake and create new point similar to what you did.  Check the Fill volume of the graded region and see if is is the same or close to what you had with the first try.

The reason is that the official Autodesk document recommends creating identical copy when doing graded region.

I created a screencast from the example file attached.

[roscopeco2000]

Toandn you are a legend as ever, I did it this exact way it worked better this way, than the perimeter method

[ToanDN]

I forgot to mention but you need to place the new points around the water body correctly otherwise the part above the water of the new topo will be off.  Best is keeping the floor there and turn the view to Shaded so you can visually see where the water intersects with the existing topo.

[roscopeco2000]

Yeah I did exactly that mate I sketched the lake outline as a floor boundary and set it above the topo. I then used it as a guide to sketch the boundary of the lake and set the topo points at the water level. This then gave me my fill amount it's actually a very clever feature
I look forward to using it for it's proper function if we do any delevoplments on hilly terrain.