Catchment areas with friction surface

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11-16-2018 07:03 AM
MartinDuffy1
New Contributor

I am using ArcGIS desktop 10.4. I have a shapefile of 494 points. I also have a cost surface/friction surface raster. I want to create a polygon of 13.4 hectares around each point based on the friction surface. In other words I dont want a simple buffer around each point, The polygon should look irregular as it should follow the friction values.

I also want to produce another polygon with the same points and friction surface that will outline one hours walk from the point - I think I can do this in Grass but Im wondering if there is a good way to do in in ARC

Thanks in advance for any help

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3 Replies
DanPatterson_Retired
MVP Esteemed Contributor

Are you referring to Cost Allocation—Help | ArcGIS Desktop ?

It doesn't have an area parameter but it does have a maximum distance parameter, so I am not quite sure how you can limit the allocation to area

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MartinDuffy1
New Contributor

Hi Dan

Thanks for getting back to me - its the area parameter that I am stuck on. Each point is a settlement and I want to define a polygon around it with an area of 13.4 hectares. However I dont want a simple buffer I want it to be based on the raster friction surface, so I would end up with an irregular line. In other words if there was grassland to the west of the settlement and bogland to the east, the polygon would extend further to the west.

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DanPatterson_Retired
MVP Esteemed Contributor

I would have a look at the results without the limitation of area first to see what you get

The only way I can think of offhand is to perform the cost allocation for a location with a limiting distance, then determine the area covered, if too low, increase the limiting distance and repeat

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