[Talk-GB] UK coastline data

Borbus borbus at gmail.com
Fri Jul 12 19:04:49 UTC 2019


On Fri, Jul 12, 2019 at 12:40 PM <wambacher at posteo.de> wrote:
> The old coastline (August 2018) is blue and the current coastal line
> is red.

The blue shows what I was talking about earlier where some of the
coastline was at MLWL and some was all the way up at the sea wall
(exceptionally high tide).

> The affected areas are wetlands, whose "coastline" is very complex. In
> my opinion, the problem is that this "coastline" is not static,
> because it is a natural runoff that will never be stable. It will look
> quite different after several months.

I am familiar with this area. Those areas are salt marshes and much more
stable than you might think. The main change that has happened over the
past ten years in this area is the high water marks have receded. This
is reflected in the most recent OS data that I've used. Those inlets are
deep tidal channels and definitely should be on the map. A smoothed
coastline would be a huge loss in this area.

The bits that would change a lot more are the low water levels because
this land is comprised of soft mud and sand. Unfortunately none of the
aerial imagery we have available cover these vast tidal flats. Most cut
off at the "coastline" (high water level).

Borbus.

On Fri, Jul 12, 2019 at 12:40 PM <wambacher at posteo.de> wrote:

> Hi,
>
> I don't think you should accept this data.
> see:
> https://wambachers-osm.website/images/osm/snaps_2019/strange_coastline.png_2019/strange_coastline.png
>
> The old coastline (August 2018) is blue and the current coastal line is
> red.
>
> The affected areas are wetlands, whose "coastline" is very complex. In my
> opinion, the problem is that this "coastline" is not static, because it is
> a natural runoff that will never be stable. It will look quite different
> after several months.
>
> A manually smoothed coastline (better than the one from 2018) would be
> appropriate.
>
> ym2c from germany.
>
> walter
> Translated with www.DeepL.com/Translator
>
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