Hi,

I am working on creating an elevation model for a quarry showing how the quarry would look post closure. One of the key requirements is that the slopes along the benches should be 30 degrees, for rehabilitation. For that purpose, I was thinking about extracting the elevation points along a particular boundary and exporting the attributes table to Excel. Then, based on the assumed base elevation and the elevation of each of the points along the boundary, I was wondering if I could create a new layer of points which would be the base of the slope. The points would be at a distance from the boundary such that the slope would be equal to 30 degrees theoretically; when viewed from an aspect angle of 90 degrees, relative to the quarry boundary.

Is there a general equation to calculate the XY coordinates of the points at the base, based on the coordinates of the elevation points on the boundary? For instance, let us consider a point on the boundary and a point to be placed at the base of the slope. The XY coordinates of the point at the boundary is known and the elevation values for both the point on the boundary and the point at the base are known. To obtain a 30 degree slope, is it able to obtain the XY coordinates of the base point using a general equation? Like a python code or could it be worked out in Excel?

Thanks for your suggestions.

Gaurav Dewan

You mention that the elevation values at both boundary and base are known, so I assume there is some constant elevation drop for the bench...? I'll assume 10m drop, just for illustration.

Since you know the drop and the angle, you can figure out the horizontal distance of the bench using:

So, if the bench drops 10m, it must extend 17.3m to fit a 30 degree angle. So, buffer the boundary by -17.3m to get your base boundary. From there, you can convert the buffer to line, convert line to raster, and use Con() to extract elevations at the base of the slope.