I am trying to expand existing 'tidal complexes' to include the adjacent 100-year floodplain areas. Both are rasters, and so far I've used Euclidean Allocation to identify the tidal complex closest to each pixel in the study area and extracted the output using the floodplain as a mask so that I have a raster of floodplain area labeled by the closest tidal complex.

However, I only want to include floodplain areas contiguous to the tidal complexes - some of them are farther inland and not contiguous.

enter image description here

I region grouped the floodplain area labeled by tidal complex output so that each contiguous area has a unique value, and then extracted that output using the original tidal complexes as a mask. The resulting raster has the unique identifiers for the contiguous floodplain areas underlying each tidal complex.

enter image description here

I'm stuck at this point; I need to somehow extract the floodplain areas contiguous to the tidal complexes (my current raster's extent is just the tidal complexes themselves). I originally thought that an inner join between the region-grouped floodplains and the tidal complexes identified by region-grouped floodplain ID would do the trick, but it seems to alter just the raster attribute table, not the raster itself - the attribute table only includes the region-grouped floodplains contiguous to the tidal complexes, but the raster has all of the region-grouped floodplains.

My other idea is to select the region-grouped floodplains by attribute, based on the values in the tidal complexes by region-grouped floodplain ID, but there are >200 values, and I don't know of an efficient way to extract them to use in a query.

I am working in ArcGIS Pro ModelBuilder so far, but could switch to python if necessary.

  • It's not immediately clear what you want to keep. In the second image the dark purple, cyan, light green, brown and light brown pixels below your grey tidal complex pixels, are they to be removed? They are not intersected by the grey tidal complex pixels so what is your intention with those? If this is an intersection problem then consider converting your data to vector and doing a spatial selection, everything not selected is dropped? – Hornbydd Sep 2 '19 at 14:39
  • The other colors you refer to are region-grouped floodplain areas associated with other tidal complexes not shown in the image - I zoomed in to try to keep things simple. For the tidal complex shown, I want to drop the teal floodplain area and keep only the olive, and then repeat the same process for all of the other tidal complexes in the study area (keep only the floodplain areas contiguous to the tidal complex). I'm currently working on a raster solution in python but may consider a vector spatial selection as you suggest if that doesn't work out. – kwarnell Sep 3 '19 at 15:04

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