Changeset: 30528688
UK, W of Shrewsbury, tidy riverbank and centerline of the Severn, add missing river islands
Closed by bdiscoe
Tags
created_by | JOSM/1.5 (8159 en) |
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source | Bing |
Discussion
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Comment from trigpoint
Hi
I have spotted that you have edited the River Severn in Shropshire.
The river forms parts of Montford/Ford parish boundaries and in moving the river flow you have moved the boundaries so that they no longer follow the official lines.
I am not sure what source you used to determine the main flow, although as you are no doubt aware the severn is a strange river and the widest path is not always the deepest or fastest. -
Comment from bdiscoe
Hi tngpoint, mostly this changeset was fixing the riverbanks and adding the islands. The centerline moved only very slightly; it had a few places where it did not appear to correspond to the river flow. I did the best I could using the aerial, but if you have better local knowledge, please feel free to adjust it.
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Comment from bdiscoe
Also, I notice that it isn't quite consistent; in some places the parish boundaries share a way with the river, in other places they use two separate ways; perhaps someone determined that on that stretch the "official" boundary differed significantly enough from the river. Some boundaries has the natural feature _as_ the official boundary, so in that case they should always share a way, but again, if you have local knowledge otherwise, you can make them consistent.
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Comment from SomeoneElse
I've always wondered (where boundaries follow rivers) exactly how those boundaries are defined, given that rivers move? In this case is there a text description that says something like "follows the centreline of the river from blah to blah", or is it defined in terms of exact coordinates, and updated periodically when the river moves?
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Comment from bdiscoe
@SomeoneElse, it depends :) In some places the legal boundary is defined as the river, in other places the river was surveyed and that description of the course defined as legal boundary. It takes local knowledge to know the difference in different parts of the world.
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Comment from trigpoint
The boundaries are taken from the latest OS Boundaryline, so can be assumed to indicate the official boundaries.
I part way through a project to add the Shropshire parish boundaries, some sections of the Severn have yet to be joined to the parish boundaries.
I am not sure how "the main flow" can be determined without local knowledge, it certainly cannot be by looking at bing imagery, the main flow will be the deepest channel, not the widest.
Ways (13)
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- 340826162, v1
- 340826163, v1
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- 340826165, v1
- 261953001, v5
- 261953065, v3
- River Severn (338694412), v2
- River Severn (338694413), v2
- 261953064, v3
- 338694414, v2
- 36709096, v4
261953066, v4
Relations (2)
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