topic using slope, distance and elevation to calculate point of impact on varying terrain in ArcGIS Spatial Analyst Questions

using slope, distance and elevation to calculate point of impact on varying terrain

GregEdmonds — Wed, 14 Aug 2013 13:16:34 GMT

I would like to know if there is an existing Arc tool and/or method to calculate the following:

I have a fixed point at the base of a mountain. The ground at my fixed point is not flat, though, there is a slight percent slope for the first 400m, and the slope increases more and more at higher elevations. I need to determine where a straight line drawn from my fixed point 10 degrees upward towards the mountain would intersect the mountain (elevation at intersect). I am pretty sure that I need to incorporate my starting percent slope, as well as the varying percent slopes as elevation increases.

I have been working with rise over run and SOHCAHTOA examples, but the change in slope over distance is what is throwing me.

any assistance would be appreciated.

Re: using slope, distance and elevation to calculate point of impact on varying terra

DanPatterson_Retired — Wed, 14 Aug 2013 20:21:25 GMT

3D Analyst Profile tool will allow you to extract the necessary information for further analysis. The SA doesn't have such tools.

Re: using slope, distance and elevation to calculate point of impact on varying terra

ChrisSnyder — Wed, 14 Aug 2013 23:36:10 GMT

I could see a Spatial Anlayst solution using a line FC drawn from the point to the (?) summit and a eclidean distance raster eminating from the point.

You would basically build a crosssection of elevations along the line (x axis = elev, y axis = distance along the line from the point).

The questions then is at what distance along the line does the elevation of the mountain become greater than the elevation of a 10 degree vertical slope along the same line.

Nothing out box for this as far as I know, but certainly doable... 1st step would be to build a cross section.