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I would like to split a raster DTM of a river valley into several (maybe 30) equal sections. The raster currently follows the river channel and so is not a straight line but bends and moves like a river. Is there a way for me to split this raster into equal sections which can then be analysed individually? I tried the split and divide tools but these only work for polygons/lines. I am unsure how to divide the raster equally and/or into a specific number of sections. I almost want it to be in a grid-like format.

So for example, I have a section of the river: enter image description here

And would like to split it up (for example) as so - I did this by calculating the Euclidean Distance: enter image description here

As if each colour was its own section that I can analyse individually.

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    I have added to the original post – xxenox Jul 15 at 15:45
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Create raster with cell values of 1 using raster calculator, e.g.

Con(~IsNull("dem"),1)

Draw section at stream 'mouth' and use above raster as cost surface and section line as input feature for Cost Distance tool. You'll get something like this:

enter image description here

Convert raster to points and remove unwanted points downstream from section line. Sort points in ascending order of values in field "grid_code". Populate new short integer field using something similar to:

!OBJECTID!//249

I used 249 in above because I have 2489 points and decided to split them into 10 same size clusters:

enter image description here

Table in a upper right corner is table of a raster derived by converting points back to raster, using values stored in new field.

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You can use Split Raster in the Data Management toolbox. https://pro.arcgis.com/en/pro-app/tool-reference/data-management/split-raster.htm

Within the tool you can specify the output raster size, number of tiles, or use a polygon feature class (i.e. a fishnet). The tool requires that you specify an output folder and base name for each resulting raster.

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  • Thanks but for this it seems that I require an output raster size which I am unsure how to define. Would I have to individually outline each section I want to split before I can use this tool? For example, if I wanted a new section to begin every 100m, would it require me to have already made this template somehow.. – xxenox Jul 15 at 15:45
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    My apologies - I didn't fully understand your question. SE user @phloem made a python script that I think will help you subdivide the area of interest logically: <gis.stackexchange.com/questions/114204/…> – Drbeene Jul 15 at 16:49
  • It sounds like you could play around with the slice points to make it fit your goals, since there's no pre-determined formula that will give you the size. You could reclassify that raster of Euclidean distance (e.g. 0-50m = 1, 50.1-100m = 2, etc.), and then turn that into the polygon that defines the raster size for Split Raster. Alternatively, you could place points at regular intervals down the river centerline, and create Theissen Polygons to find all the area closest to that point. The Theissen Polygons could be the size you use for Split Raster. – Mon Mo Jul 15 at 21:02

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