topic Raster analysis following flow direction in Water Resources Questions

Raster analysis following flow direction

MiguelLlorente_Isidro — Mon, 11 Feb 2013 09:50:37 GMT

Hello,

I am trying to obtain a raster dataset out of this analysis: for each pixel in a raster I want to substract value of the previous pixel according to the flow direction.

Lets say pixel A flows into pixel B. Pixel A has a value of 3 and pixel B has a value of 4. I'd like to get a raster where in pixel position of B I have a value of 1. For all those pixels where there is no previous pixel flowing into it, it should return a value of 0.

Any thoughts? Thx!

Re: Raster analysis following flow direction

MarkBoucher — Mon, 11 Feb 2013 19:10:36 GMT

I commented on another thread where the user wanted to analyze the values around a grid cell. I found the "Shift" tool. http://forums.arcgis.com/threads/75804-surface-angle-in-each-cardinal-direction?p=265962&viewfull=1#post265962

You might be able to do the same by instead of just the 4 directions (N, S, E, W) that this user was wanting to deal with, you could make fdr grids for each of the 8 directions. Then use the the Con() function with the flow direction grid as the test to determine which of the 8 grids to do the math with. The logic is probably simple and model builder could make it easy to via trial and error.

Re: Raster analysis following flow direction

MiguelLlorente_Isidro — Mon, 11 Feb 2013 22:44:25 GMT

Hello MBoucher21, thx for your uberfast reply.

I was getting "range" out of Focal Statistics with a 2x2 neighbourhood applied solely to the river network and I was having some inconsistencies due to river proximity. Your suggestion worked like a charm.

Regards,