Pt. 509.8m (SN 827 479) – Welsh Highland
Sub addition
There has been an addition to the listing of the Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height
and their locations, the drop and status of the hill derived from LIDAR
analysis conducted by Aled Williams.
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LIDAR image of Pt. 509.8m (SN 827 479) |
The criteria for the list that this addition applies to are:
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Welsh Highlands - Uchafion Cymru by Aled Williams and Myrddyn Phillips |
The hill is being listed by the point (Pt. 509.8m)
notation, and it is adjoined to the Drygarn Fawr group of hills, which are situated in the northern part of South
Wales (Region B, Sub-Region B1), and
it is positioned with a minor road to its north-west and east, and the A483
road to its south-east, and has the town of Llanwrtyd towards the east
south-east.
When the initial P10 sub list was completed in
June 2020 this hill was not listed as contour configuration did not give it
sufficient interpolated drop for it to be included, with the contemporary
Ordnance Survey 1:25,000 Explorer map having an uppermost 500m ring contour
that also connects with its critical bwlch.
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Extract from the Ordnance Survey 1:25,000 Explorer map |
However, it was not until LIDAR became available
that the details for this hill could be accurately re-assessed. The LIDAR (Light Detection & Ranging)
technique produced highly accurate height data that is now freely available for
much of England and Wales.
Therefore, the addition of this hill to Welsh
Highland Sub status is due to LIDAR analysis, resulting in a 509.8m summit
height and a 499.5m bwlch height, with these values giving this hill 10.3m of
drop, which is sufficient for it to be classified as a Welsh Highland Sub.
The full details for the hill are:
Group: Drygarn Fawr
Name: Pt. 509.8m
OS 1:50,000 map: 147
Summit Height: 509.8m
(LIDAR)
Summit Grid Reference:
SN 82700 47937 (LIDAR)
Bwlch Height: 499.5m (LIDAR)
Bwlch Grid Reference:
SN 82706 47648 (LIDAR)
Drop: 10.3m
(LIDAR)
For the additions, deletions and reclassifications to the Welsh Highlands – Uchafion Cymru
reported on Mapping Mountains please consult the following Change Registers:
Welsh Highland P15s
Welsh Highland Subs
Aled Williams and Myrddyn Phillips (January 2024)
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