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jpccrodrigues

Designing a Small Dam | Flood Area

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Hi guys,

 

I'm developing a small dam for agriculture use. I have the site model done, the place for the dam and its height. Is there a simple way to get the flooded area? And its volume (I'm pushing it!!)?

(the water plan in the image has change)

 

image.thumb.png.20abdf4c8e8dc3bffcaff91369b907ef.png

 

Thanks!!!

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Create an extruded shape (probably a rectangle or polygon) that has a surface at the water level you want. Make sure the extrusion is deep enough so the bottom is below the lowest point on the DTM.

 

Select the extrusion and the DTM and Subtract Solids. You should now have a Solid Subtraction equivalent to the volume of water being retained by the dam. 

 

Volumetric Properties from the Model menu will give you the Volume of the solid.

 

Extract Surface will give your a NURBS surface of the top of the water. Modify Menu:Convert:Convert to Polygon will give you a polygon which will show the area in the OIP.

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Hi Pat,

 

When I try to do the subtraction operation it gives me  an error stating "You have tried to create a solid object which cannot be computed. Edit the geometry to resolve this condition and try again".

I send a file with the two objects so you can take a look.

Thanks for your support.

2020_03_26_MODEL_DAM.vwx

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Posted (edited)

@jpccrodrigues

1.  Make a copy of the layer with the extrude and the Site Model.

2. (optional) In order to speed up the Solid Section in step 7 below, trim away the site model around the extrude with the Split tool.

3. Select the Site Model>Ungroup>accept the warning.

4. Result is Skirt, Contours (group), and Mesh

5. Delete the Skirt and Contours

6. Select the Mesh and the Extrude

7. Section Solids - make sure the Mesh is highlighted.

8. Result is probably the volume below the mesh. Click the OIP "Reverse Sides" button.

 

For some reason this solid does NOT report a correct Volume in the Volumetric Properties dialog.

I tried sectioning with a Drape Surface of the Mesh and some other things.  Volume never correct.

Maybe others can sort that out.

 

Post with your results.

-B

 

 

 

 

 

 

Site Model Section.png

Solid Section Reverse.png

Edited by Benson Shaw
text edit
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How about this:

 

Draw the shape of the water area in 2D, layer plane.

Raise the shape up to the top of the water.

3D tool set > Project > 3rd mode, pointed down in the second group of modes.

 

That should get you a generic solid with exactly the volume of the water.

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Hi Guys!!

 

Followed the procedure that @Benson Shaw presented and then consulted "Model- Volumetric Properties" So, I think I got 19.640 m3, value that seems realistic.

 

image.thumb.png.a87791bf6c42c7afb1128542d1635b68.png

 

Thank you for the help!!!

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This functionality is already built into the Site Model:

  • Create a Site Modifier>Pad with Retaining edge by extracting a Polygon from the 96m contour.
  • Offset this to create a Site Modifier>Grade limit a small distance eg 10cm outside the Pad
  • Update the Site Model
  • Update Cut & Fill Calculations
  • I get 21,788m^3 but my Polygon is slightly different to the original.

 

  • image.thumb.png.e1ff3bb494dbb5d00d8eb3119b846dcd.png

image.thumb.png.f3ae22b3c562db66f6274bcf4ab3eea9.png

 

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@jpccrodrigues - Glad you made this work.  Check that volume, though. I was skeptical of the reported value  because I made a (wrong) estimate.  I now believe the volume report is correct for the shape.  My shape reports 24000 m3 (note to all: US math places a comma for thousands separators, many others use a period as the thousands separator, so 24,000 US = 24.000 in many other places). Several things could cause the differences in reported volumes:

Smoothing angle of the mesh, lowest point of the site model skirt, lowest point of the extrude.  I see that your site model low point is set to 70 which corresponds to the lowest contour.  I adjusted my site model min elevation to 10 so that bottom of pond is not right at extent of the site model skirt. My terrain developed a slightly deeper depression at bottom of pond. I placed bottom of my extrude at 10 as well.

 

@michaelk - This process with the Project tool works to generate a volume, but I think it requires a section through the terrain at top of dam to generate the shape of the surface of the water. Unless you have another way to generate the shape? I think this still requires ungrouping the site model to create a mesh and subsequently performing a Solid Intersection or Solid Section.

 

@bcd I like this! But it destroys the contours at bottom of pond. Maybe just use this on a duplicate layer to calculate the volume and use other means to display the pond bottom and water graphic?  I think more accurate water surface contour depends on the dam being in place to generate that contour shape. What might be the best work flow? Edit that 96 contour to represent inner shape of the dam? Or use a Pad raised to top of dam?  Or add the pad to represent the dam and create new contours from that and generate a new site model or ???  There is probably something really simple.

 

All - I seem to remember being able to make solid operations directly with the site model in Mesh mode.  Did something change in v2020? or is that an incorrect memory???  Or just something about this site model? It doesn't seem too far from Origin.

 

-B

 

Min Elevation.png

Extend Skirt.png

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19 minutes ago, Benson Shaw said:

@jpccrodrigues - Glad you made this work.  Check that volume, though. I was skeptical of the reported value  because I made a (wrong) estimate.  I now believe the volume report is correct for the shape.  My shape reports 24000 m3 (note to all: US math places a comma for thousands separators, many others use a period as the thousands separator, so 24,000 US = 24.000 in many other places). Several things could cause the differences in reported volumes:

Smoothing angle of the mesh, lowest point of the site model skirt, lowest point of the extrude.  I see that your site model low point is set to 70 which corresponds to the lowest contour.  I adjusted my site model min elevation to 10 so that bottom of pond is not right at extent of the site model skirt. My terrain developed a slightly deeper depression at bottom of pond. I placed bottom of my extrude at 10 as well.

Yeah, in fact following your indications it gave me the 24.000 m3 of volume.

 

Thank you very much for the help everbody!!

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