[Talk-GB] District Boundaries - N Wales
Peter Miller
peter.miller at itoworld.com
Sun Aug 23 17:13:04 BST 2009
On 23 Aug 2009, at 15:50, Chris Hill wrote:
>
>
> Peter Miller wrote:
>>
>>
>> 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.
> The biggest problem with aerial photos is that you don't know what
> the state of the tide was at the moment the photo was taken. You
> can sometimes guess a high water mark on a beach by the strand line,
> but low water is always covered except at low water.
So we need to commission a satellite to take photos every 30 minutes
for a 12 hour period for the whole of the UK at the appropriate time
of the lunar cycle - we haven't even discussed if we are should be
using neap times or spring tides or the mean of the two.
But really, I think we are starting to spit hairs here!
<snip>
Regards,
Peter
>>
>> Regards,
>>
>>
>> Peter
> Cheers, Chris
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