[Talk-GB] District Boundaries - N Wales

[Peter Miller]

On 22 Aug 2009, at 12:03, Chris Hill wrote:

> Well I'm pleased that they agree with me, but I'm not the oracle!   
> This is another source quoting the same general information.  Do the  
> Scottish and Northern Irish counties generally extend to the low  
> water mark too? Drawing from the NPE maps seems to be our only  
> reasonable source for the low water mark.

Great stuff.

Low water does however change much more rapidly that high water so NPE  
is the 'least good' source of that date as it is 50 years old. If one  
is fortunate enough to have detailed enough recent aerial photography  
that that should be used.

Fyi, for Suffolk the low water mark has changed by 50 meters in places  
in the past 5 years (huge amounts of shingle has arrived near  
Felixstowe Ferry extending low water by that amount since I have lived  
in the area). Even the high water mark has moved by many meters over  
50 years in some places including Dunwich. One can see the different  
in Potlatch comparing the OSM coastline with NPE base mapping.

We have good yahoo aerial photography for pasts of the coast in Suffolk.

However... I support the idea we use best low-water source availale  
for each area. It might be good to create areas between high and low  
water tagged with 'shingle', 'beach' etc.

Should be also use low water as the edge of 'Wales' itself or has any  
evidence for the 3 mile limit mentioned by the wiki by someone been  
found?


Regards,


Peter


>
> Bogus Zaba wrote:
>>
>> I have had confirmation from the Local Government Boundary  
>> Commission for Wales who agree with the view below from Chris Hill.  
>> They say :
>> "...in general the seaward extent of a local authority is the low  
>> water mark as defined by Ordnance Survey. The exception to this are  
>> certain islands such as Flat Holm (which comes under Cardiff),  
>> where the courts have made specific decisions, such as Milford  
>> Haven, and where the Secretary of State has made an Order extending  
>> the local authority boundary to include an area of the sea (under  
>> Section 71 of the 1972 Act). As far as I am aware no such orders  
>> have been made in respect of Welsh local authorities."
>>
>> That's good enough for me. I will define the low water mark from  
>> NPE and use that in the Flinthsire and Denbighshire boundaries.
>>
>> Bogus Zaba
>>
>> Chris Hill wrote:
>>> I have researched boundaries of the English counties and unitary  
>>> authorities.  it seems that generally they follow the mean low  
>>> water mark.  Some of the land is owned by the council, some by  
>>> private owners but often by the Crown Estates and leased to the  
>>> council.  By using the low water mark the council administers the  
>>> beach or foreshore and the Crown Estates administer the seabed  
>>> beyond.
>>>
>>> Cheers, Chris
>>>
>>> Bogus Zaba wrote:
>>>> I have completed the following relations for Unitary Authority  
>>>> Boundaries and put them in the Wales Wiki : Wrexham (137981),  
>>>> Flintshire (198566) and Denbighshire (192442). Now some  
>>>> inevitable questions:
>>>>
>>>> 1. How should Flintshire and Denbighshire be completed out at  
>>>> sea? On the Wales Wiki it says "The current Wales Boundary (08  
>>>> July 2009) is both wrong and unhelpful." So I guess I should not  
>>>> be using that. Currently Unitary Authority boundary lines go out  
>>>> to sea traced from the NPE, but they do not join up with any  
>>>> coastal boundary. As it happens in this part of NE Wales, nobody  
>>>> seems to have made the coastline (high water mark?) ways to be  
>>>> members of the national boundary relation, although that has been  
>>>> done for about 70% of the welsh coastline.
>>>>
>>>> 2. In putting together the relations for these boundaries I found  
>>>> myself splitting a lot of roads and streams into relatively short  
>>>> sections so that I could then make these sections members of the  
>>>> boundary relation. Is this recognised good practice, or is it  
>>>> better to make a separate boundary way which simple shares nodes  
>>>> with the relevant stream or road etc ?
>>>>
>>>> 3. In doing all this I have used the NPE layer which can be used  
>>>> as a backdrop in josm and potlatch. I have realised that this NPE  
>>>> is not the same NPE as can be found in other places (eg the  
>>>> postcode collection application at http://www.npemap.org.uk/).    
>>>> The latter is clearer than the  tiles in josm and potlatch  
>>>> especially regarding parish boundaries (which you find yourself  
>>>> tracing) which are nice dotted lines in the postcode application  
>>>> and faded grey lines in the josm/patlatch layers. Can the clearer  
>>>> (newer?) tiles be made available in the osm editing environments ?
>>>>
>>>> Thanks
>>>>
>>>> Bogus Zaba
>>>>
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>>
>>
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