[Tagging] Coastline for rivers, estuaries and mangroves?

Joseph Eisenberg joseph.eisenberg at gmail.com
Wed Sep 5 01:33:20 UTC 2018

Colin and Christoph, could you give some guidance about a couple of
the specific situations that I brought up in the original post?

First, in the question on the help Q&A board, the other mapper wanted
to remove the coastline from tidal parts of rivers in England , so
that the end of the waterway=river would meet the coastline. It looks
to me that this is contrary to standard mapping in England and many
other places. But I can see why some people look at the waterway line
out beyond the coastline and feel it needs the river area mapped.

Would mapping the water area of the river all the way down to the
mouth be a good solution? This would be extra work in the ID editor,
but quite simple in JOSM. It would lead to having two ways on the
riverbank from the mouth to the end of the coastline: both
natural=coastline and natural=water (or waterway=riverbank), but then
it would be easier to calculate the total surface area of a river
include it's estuary and tidal portions, for example.

It seems like this would be reasonable, if the coastline is considered
to map the furthest inland limit of the marine environment (at high
tide), and the river area plus the line of the waterway are mapping
the longest extention of the river.

Has this method been used extensively?
-Joseph Eisenberg

Date: Mon, 03 Sep 2018 23:40:02 +0200
From: Colin Smale <colin.smale at xs4all.nl>
To: tagging at openstreetmap.org
Subject: Re: [Tagging] Coastline for rivers, estuaries and mangroves?

>On 2018-09-03 23:08, Christoph Hormann wrote:

>> On Monday 03 September 2018, Colin Smale wrote: This is essentially the situation we have right now.  Judgement of
>> local mappers is usually fine (with the exception of political
>> cases like the Rio de la Plata).  Most problems occur because
>> armchair mappers misinterpret the local situation or when
>> inexperienced mappers are unaware of the significance of
>> distinguishing between ocean and riverbank mapping.
>> What guidance do we give to the local mappers?

>What is currently written on the wiki which includes the proposal which
>is linked to from the coastline documentation.

>> Given a properly formulated rule-of-thumb, why should remote armchair
>> mappers come to a different conclusion to local mappers in this case?

>As said this is mostly due to misinterpreting imagery.

That can account for a few metres either way (perpendicular to the
shoreline), but not for the difference between tidal limit and a
"convenient crossing point near the sea". That is purely a personal
judgement, not misaligning imagery. After all, we are not disputing here
the location of the sides of the river, but where we draw the line from
one side of the river to the other.

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