Deriving Slope Position

Question

I'm currently running an analysis to determine structure locations (which are polygons) relative to slope positions. I need to determine if they are a) at the bottom of a slope b) Mid-Slope on a bench c) Mid-Slope continuous or d) on the upper portion of the slope.

Any ideas would be great, thanks ahead of time.

Anonymous User · Answer

Wow! What a fantastic tool/extension Mervyn - Thank you so much for passing this information along.

I was working with a DEM produced from TRIM Data for this project - I'm going to test it on an area with with LiDAR data and I can't wait to see the results.

MervynLotter · Answer

You can also use the Topographical Positional Index (TPI) to determine position along a slope. If you are using ArcMap, then there is a really useful add-on that was developed by Jenness Enterprises that will easily calculate and categorise this for you. The add-on is free and part of the Land Facet Corridor designer tool. See Jenness Enterprises - ArcGIS Tools; Land Facet Corridor Designer

The Slope Position 3-category output may give you what you are looking for.

The documentation is really good and will help with the installation and setting some of the parameters.

If you are using ArcGIS Pro, then you can more-or-less accomplish the same thing using Focal Statistics and Raster Calculator, you will just need to categorise the output yourself afterwards.

DanPatterson_Retired · Answer

I am familiar with the context, my procedures are to delineate those 'candidate areas'

After this stage, you can use bounding containers of some incarnation (eg minimum area bounding rectangle, minimum area bounding ellipse ) which will give you the orientation of the areas and the long and short axes of the oriented container.  If all goes well, then you will have the upslope axis, from start to finish.  That will give you the midslope position.

If the mid-slope axis connects to a flat area top and bottom (meeting your criteria for flat), then you have your information.

If you complete what I suggested, showing a map of you results relative to the terrain may provide a discussion point.  (PS, there are fire modelling tools out there, I just don't remember if they are gis based or not)