Drum Boeth (SH 720 462) - 500m Sub-Uchaf reclassified to Uchaf
There has been a reclassification to the listing of Yr Uchafion, with the summit height, bwlch height and their locations, the drop and status of the hill derived from LIDAR analysis conducted by Aled Williams, with a subsequent Trimble Ge0XH 6000 survey conducted by Myrddyn Phillips and Aled Williams confirming its status.
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| The Trimble GeoXH 6000 gathering data at the summit of Drum Boeth (SH 720 462) |
The criteria for the list that this reclassification applies to are:
Yr Uchafion (Latterly named The Welsh Highlands - Uchafion Cymru) - This is the draft title for a list of the Welsh 500m P15s that takes in all Welsh hills at or above 500m in height that have a minimum 15m of drop. Accompanying the main list are three sub lists; the 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub-Uchaf category. The criteria for 500m Sub-Uchaf status is all Welsh hills at or above 500m in height that have 14m or more and below 15m of drop. The list is co-authored by Myrddyn Phillips and Aled Williams, with the details relating to this list published on the Mapping Mountains site in November 2015.
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| The Welsh Highlands - Uchafion Cymru by Aled Williams and Myrddyn Phillips |
The name the hill is listed by is Drum Boeth, and it is adjoined to the Arenig Fach group of hills, which are situated in the central part of North Wales (Region A, Sub-Region A2), and it is positioned with the A470 road to its south-west, and has the town of Blaenau Ffestiniog towards the south south-west.
This hill is given an uppermost 520m ring contour with no spot height on the contemporary Ordnance Survey 1:25,000 Explorer map, with bwlch contouring between 500m – 510m and therefore it was prioritised for a basic leveling survey. This was conducted by Myrddyn Phillips on the 27th October 2005, resulting in 48ft 6˝ (14.8m) drop and its inclusion as a 500m Sub-Uchaf.
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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.
LIDAR analysis resulted in the reclassification of this hill to Uchaf status. The hill has subsequently been surveyed using the Trimble GeoXH 6000, and it is this result that is being prioritised for listing purposes.
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| The Trimble GeoXH 6000 gathering data at the bwlch of Drum Boeth |
Therefore, the reclassification of this hill from 500m Sub-Uchaf status is due to LIDAR analysis, with a subsequent Trimble GeoXH 6000 survey confirming its status, resulting in a 523.4m summit height and a 508.1m bwlch height, with these values giving this hill 15.2m of drop, which is sufficient for Uchaf status.
The full details for the hill are:
Group: Arenig Fach
Name: Drum Boeth
OS 1:50,000 map: 115
Summit Height: 523.4m (converted to OSGM15)
Summit Grid Reference: SH 72020 46289
Bwlch Height: 508.1m (converted to OSGM15)
Bwlch Grid Reference: SH 72159 46335
Drop: 15.2m
For the additions, deletions and reclassifications to the The Welsh Highlands – Uchafion Cymru reported on Mapping Mountains please consult the following Change Registers:
Myrddyn Phillips and Aled Williams (April 2017)
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