I need to create a buffer around waterfront park sites. But I only want "half" of the buffer --- the "half" that coincides with the side of the water body where to park is.

In addition, the buffer of one park may overlap another due to their proximity. I would like to have just one "half" buffer for each park.

I tried to buffer the parks, union them with waterbody, erase waterbody, select by location the buffer using the parks. But since the buffers overlap, they create multipart features and only one or two parts of the buffer are selected.

Below is example of what I am talking about.

For the park (green) on the left I would like a half buffer to the north (assuming north is up) and no buffer south of the waterbody.

For the parks on the right (one big and one small) I would like two separate buffers that are each single part features.

ps these are both polygon vector files and I have an advanced license

enter image description here

EDIT: @ChrisW s method: enter image description here

  • 1
    How proportionally wide are these buffers in relation to average width of the main river? Double or triple the width? I would draw a line down the approximate center of the river and create a left/right hand buffer of the line (which buffer will do). Make the buffer wide enough to at least touch every buffer that could cross the river, and preferably entire cover every future buffer. Attribute left vs. right buffer and spatial join to polygons. Buffer those polygons and erase the buffer on the side opposite the attribute, then erase the river itself. Should leave buffers on one side. Commented Feb 26, 2015 at 20:23
  • 2
    You can specify right or left side in the buffer tool in ArcToolbox. This does not work with the Buffer dropdown on the Editor toolbar. You can specify Outside only as well.
    – recurvata
    Commented Feb 26, 2015 at 20:25
  • 1
    Do it with the tool. You only need left and right side buffers for the entire river centerline to be created once, not for any of the polygons along the river. You have to create a special line feature type to make this work. (rest of post erased. I though recurvata's comment was from the original post author). Commented Feb 26, 2015 at 20:31
  • @Richard Fairhurst Cool, i did not know about left/right buffer, but I don't think it will work. The streams vary a lot in width and there are parks adjacent to ocean, which would not have a centerline to buffer around Commented Feb 26, 2015 at 20:35
  • A coastline can have a centerline (all centerlines are imaginary 2D human constructs, and none actually exist in nature, so make one anywhere in the world you want one). The centerline just has to stay inside the river/ocean boundary off land. Put each line's buffer width in a field to vary the widths. Adjust each centerline buffer width enough to cross the river edge or coastline on to land on each side. Erase the river first then select any park polygon that spatial joined the left buffer with the line right buffer and vice versa and deleted it. All wrong side polys will touch it. Commented Feb 26, 2015 at 22:13

1 Answer 1

  1. Buffer the parks the desired distance with Dissolve type set to NONE. You should have individual buffers for each park.
  2. Erase the waterbody layer from the buffers. Erase requires an Advanced license, but you've already mentioned using it.
  3. Explode or Multiparts to singleparts the remaining buffers. This splits any multipart features where a buffer was so large it went all the way across and beyond the river.
  4. Select by location all buffers that do not intersect a park and delete them. These are those across the river pieces. Some of them won't get selected in cases like that tiny park on the north side east end of your image.
  5. Open the buffer attribute table and examine the buffer/feature ID (the attribute that gives the ID for the feature it was created from). Either by sorting the table on that field, or using a summarize with a count on it (or Summary Statistics if you want a separate table to look at) determine which of the original buffers still have more than one piece. You'll know because there will be two rows/records with the same ID. Hopefully there aren't too many of them, and you can visit each and delete the appropriate one. If there are a lot or for a more automated approach you'd be looking to select all buffers where they intersect a park and the ID doesn't match.
  • 2
    If he has an advanced license, he can just use the Left or Right option for the line side.
    – crmackey
    Commented Feb 26, 2015 at 21:06
  • @crmackey no, he cannot, because his river is a polygon and left/right is only valid for lines. He would first have to convert the river polygons or ocean to lines, or draw a line to use. Comments have already stated this is not feasible.
    – Chris W
    Commented Feb 26, 2015 at 21:12
  • No one has said it is infeasible that I can see. The lines need not be accurate in any way other than that they stay inside the river. An LR network also should be part of his tool set if he wants to monitor any events on his rivers (Polygons suck for that, as proven by the fact that I could never keep up by using road casings to track events on my road network, but can easily with LR). If this is a primary assignment then everything becomes feasible when we get tired of doing too many manual steps over and over and decide to put the time into things that save time in the long run. Commented Feb 26, 2015 at 23:58
  • @ChrisW I tried what you mentioned. When I select by location all buffers that dont touch the park, I only get some of the single part features of the buffer because so many of them overlap. I inserted a picture of that in the original post. Commented Feb 27, 2015 at 14:08
  • @ChrisW also my "parks" file is not finalized and I will most likely be adding and deleting from it. So an automated model would be a lot more ideal than manually sifting through the attribute table Commented Feb 27, 2015 at 14:11

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