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<p>On 2019-07-11 22:45, Borbus wrote:</p>
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<div dir="ltr">On Thu, Jul 11, 2019 at 9:19 PM Colin Smale <<a href="mailto:colin.smale@xs4all.nl">colin.smale@xs4all.nl</a>> wrote:<br />> * Coastal admin boundaries (the "Extent of the Realm") are usually MLWS,<br />> but there are such things as "seaward extensions" which extend the<br />> "realm" further into the water. Check out for example Brighton Marina,<br />> Torbay, City of Bristol.<br /><br />I have noticed the boundaries often correspond with MLW. I have tried to<br />leave the boundaries alone even when they overlap with the MLW because I<br />thought combining them might be confusing.</div>
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<div dir="ltr">Combining them might actually be the right thing to do. As a matter of law the local government jurisdiction extends to MLWS (except where explicitly otherwise defined) so it should be a question of choosing the best data, probably the data from the most recent survey. Don't forget sandbanks and other areas that fall dry at low water - these are also marked by the OS with MLWS and are therefore admin boundaries.</div>
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<div dir="ltr">> * Where the "coastline" crosses the mouth of a river or estuary, there<br />> has been lots of discussion about this in the past, as usual without a<br />> clear definitive verdict. The OS data will take you upstream to the<br />> tidal limit of rivers, which sometimes gives results which some people<br />> find undesirable. Example: River Dart in Devon.<br /><br />Yes, this was something I meant to ask as well. Often the coastlines<br />cross the rivers at completely arbitrary points. Thinking about it too<br />much brings up the famous coastline paradox. Mapping it right back to<br />the tidal limit does seem like the only way that isn't arbitrary. The<br />Dart cuts the coastline off right at the mouth, which doesn't seem right<br />at all to me. It would be good to be consistent.</div>
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<div dir="ltr">I couldn't agree more! My vote is to go back to the tidal limit, for exactly that reason.</div>
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<div dir="ltr">Cheers,</div>
<div dir="ltr">Colin</div>
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