Removing slivers after splitting a polygon with a line

Question

Image 1 shows before editing. Image 2 shows 'edited line which i used too split with and with labels Close up in 3rd image.

I often split polygons with a line (ArcGIS 10.1 Split Polygon tool). In this case, and as an example: The polygons' boundary is coincident with a line (river); and opposite sides of the line/river. I re - digitise (to improve accuracy) the river and smooth the line. I then use this line to split the adjacent polygons. Often MANY small polygons (100+) are created and these are extremely cumbersome to manually integrate with the correct 'big polygon' they should be merged with. They are so small that it is by labeling them, they can be seen easily.

I usually seect them mannually and merge them with the correct polygon.

Answer 1

Split is the wrong approach for this sort of thing, for just the reason you have found (all those slivers). There are several ways to approach the problem. You might want to take a look at the help files on common editing tasks such as this one to get some ideas of different tools and methods available.

One, and probably the best for a single-pass operation, is to use topological editing. In this way you can reshape all three boundaries (the river and both adjoining polylines) in a single edit operation. Map topologies are supported even at the Basic level, but Standard and Advanced offer even more functionality.

Another approach is to reshape (different) (or redraw as you are doing) your river, then reshape the adjoining polygon edges using one of several methods. The Trace tool works; or you could reshape the polygon and not pay attention to the river beyond making a quick two or three vertex edit that makes sure the entire boundary goes past the river, use the split then, and delete your two extra polygons (possibly Clip with no delete required - I haven't done this type of digitizing in a while). You can also use Replace Sketch while editing the polygon with the river line selected.

One tip I would give for many of these methods is to do sections at a time rather than try to do an entire edit at once. The longer you're in an edit command, the more effort you stand to lose if something goes wrong.