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How do you calculate all the least cost pathways that exists for a region? I would like the output map to display all routes (and was wondering whether this can be done in one set of operations). I want to determine this by taking into account two things: slope and valley floors.

I have been informed that I need a DEM raster, and distance rasters to valley floors and rivers. I have a river system shapefile (once is in a polygon and the other is in a line format) but I don't know exactly how to create these rasters. As it stands, this is what the DEM raster and the riverways shapefile look like:

enter image description here

I have followed the tutorials in ArcGIS help 10.1 but I just don't seem to be going anywhere. I am able to create least cost pathways between two points based solely on slope, and I have tried reclassifying via building models but have been unsuccessful in creating images that display meaningful results - I think the biggest issue is inputting or creating distance rasters to valley floors/rivers and combining that with the slope raster.

Can anyone explain in layman's terms how I could create distance rasters to valley floors/rivers from a polygon or line shapefile and how this can be combined with a slope raster to create an output map displaying all existing least cost pathways for a selected study area?

Please, any help, advice, suggestions or comments would be immensely appreciated!

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marked as duplicate by whuber Dec 3 '13 at 13:58

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You can create the distance raster using the Euclidean Distance tool, then you can combine that with your DEM using raster calculator and it looks like you already know the rest

  • Thank you so much for that! one question though: to use the Euclidean Distance tool should the river shapefile need to be converted to a raster using conversion tools> to raster>polygon to raster? – user19622 Dec 2 '13 at 13:25
  • No as I remember you can use the polyline – whatahitson Dec 2 '13 at 13:37
  • Thanks, I just tried that and used the DEM raster calculator (the operation I used to combine was 'add'), then I performed slope analysis on the raster and got the results - I added a new image to the original question section - but I am still confused as to how I can now display all the least cost pathways that exist for this region. Will you be able to tell me the steps I need to take to achieve this? I would appreciate any advice! – user19622 Dec 2 '13 at 13:42
  • Sorry just had a look into it and you are best off converting for rivers to a raster grid before doing the eulidean distance Also a possibly easier alternative to raster calculator is to just add them together in the python window like costsurf= riverdist + DEM (but they need to be of the same scale first - eg 0 -1) What I'd then do is create a costdistance (tool of the same name) which will show the a raster of least cost path away a point (in all directions) from a point You can then run costPath and Id suggest raster_to_polyline – whatahitson Dec 2 '13 at 13:57
  • Thanks for that - but sounds complicated because i have never used python before. Just to break it down a bit and make it easier for me to understand the first step is to convert river shapefile to a raster using conversion tools> to raster>polygon to raster. I am sorry but the next few steps you mentioned just ran over the top of my head - is there any chance you could explain that a little bit more simpler - sorry!! – user19622 Dec 2 '13 at 14:01

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