Buffer polygon dataset on one side but in variable directions

Question

I have a polygon layer composed of ~140 polygons of varying sizes and shapes (the greenish in the image) along the coast, plus a polygon of the state itself (the bluish in the image). Basically, I need a shoreward buffer of the green polygons - so a buffer of 250 m on each green polygon, but only on the side of the polygon adjacent to the large blue polygon. I would like to find a way to mostly automate this process, if at all possible. Like maybe if I add the angle/direction of the blue polygon to the attribute table of the green polygons, maybe there is code that could specify the buffer goes in that direction only?

Additionally, the shoreward buffer must have an alongshore span equal to the alongshore span of the polygon itself (so like flat ends, not rounded). Like this:

I'm using ArcGIS Pro and have access to an advanced license. Appreciate any help or ideas 🙂

DavidPike · Answer

Yes, it would be the new buffer you clip to the yellow features.  This should produce a thin sliver of a polygon which runs along the shoreline and extends a few metres (whatever distance you buffered by) offshore.

You then buffer that, then finally clip to the State Polygons (so that it's all inland).

KaraG · Answer

I could definitely manually delete the perpendicular lines, but I was just wondering if there was any way to automate the whole process.

When you say run the buffer (flat end option), is that referring to the new buffer clipped to the yellow features?

Thanks!

DavidPike · Answer

Manual editing to get the Polylines seems like the most foolproof way if this is only a small number of features.  You mention the perpendicular lines being an issue.  Why not delete those segments after splitting the lines?

You could also buffer the State Polygons by a few metres, then Clip that new Buffer to the Yellow features, then run your Buffer (Flat end option).  Finally Clip that Buffer to the original State Polygons.