How do I make a constant slope Elevation Model in ArcMap?

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03-19-2015 10:00 AM
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GauravDewan1
New Contributor

@Hello,

I am currently working with ArcMap to develop an elevation model of a quarry showing how the terrain at the quarry site would look post-closure. One of the requirements is that the slopes placed along the benches should be 30 degrees exactly. I have an elevation model of the site and a shapefile showing all the quarry leases. One of the assumptions is that the boundary elevation shall remain the same in the future and all of the rock within the boundary would be extracted. The final base elevation is assumed to be 100m for the time-being; i.e. elevation of the pit surface post closure.

To start, I extracted the elevation points of the boundaries where the slopes shall be put in; using "Extract by Mask" and "Sample" to tabulate the values and then import them into a new template. I was wondering if it would be possible to create the points at the base of the slope using Excel; i.e. design some sort of an algorithm that will determine the XY coordinates of a point inside the boundary such that:

1. The distance between a point on the boundary and the corresponding point inside the boundary is (Boundary Elevation - 100)/tan 30deg.

2. The point inside the boundary is such that it's on a line perpendicular to the line where the boundary point is situated.

However I'm pretty sure this would take quite a lot of time and would not be the optimal way of going about the problem. As the final base elevation is subject to change, it would be better to have a solution that doesn't require much effort.

What would be the optimal way of creating the elevation model?

I have attached the shapefile showing the lease boundaries with the basemap for your reference. If I haven't made myself perfectly clear, please let me know.

Thank you,

Gaurav

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2 Replies
SepheFox
Frequent Contributor

Th is a very interesting problem, although I don't have an immediate solution. I was pondering whether some use of Euclidean distance would be useful. I will be thinking about it.

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DanPatterson_Retired
MVP Emeritus

I am sure you have seen the discussion and proposals here

  1. Creating constant slope DEM using ArcGIS Desktop? - Geographic Information Systems Stack Exchange
  2. creating a constant slope raster

the last one being Bill Huber's original ( or may predate this one) post

$$XMap and $$YMap  can be emulated using several techniques.

There's a neat trick: you can create grids of row and column indexes by performing FlowAccumulation calculations on constant grids, as in FlowAccumulation(1) (column indexes, starting at 0, increasing to the right) and FlowAccumulation(64) (row indexes, starting at 0, increasing upwards).

For your purposes that's good enough. When you really need $$XMap and $$YMap, rescale the row/column indexes by the cellsize and shift by the origin (plus, perhaps, another half a cellsize in both directions to obtain coordinates of cell centers).

No scripting needed (and much faster in execution, too)!

​and a numpy solution

and there are other solutions on GeoNet such as suggestions that Curtis, Luke and I made here

Probably enough for now

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