Sunday, 2 April 2017

Mapping Mountains – Hill Reclassifications – Yr Uchafion


Drum Boeth (SH 717 464) - Uchaf addition

There has been a new addition to the ranks of Yr Uchafion instigated from analysis of LIDAR data by Aled Williams and subsequently confirmed via a survey with the Trimble GeoXH 6000.  Yr Uchafion is the draft title for a list of the Welsh 500m P15s that takes in all hills in Wales at or above 500m that have a minimum drop of 15m, the list is a joint compilation with Aled Williams, with the details relating to this list being published on the Mapping Mountains site in November 2015.

This hill is given an uppermost 500m ring contour with no spot height on current Ordnance Survey maps and has bwlch contouring between 490m – 500m, and prior to the analysis of LIDAR data the hill was not classified.

The hill is adjoined to the Arennig group of hills with its Cardinal Hill being Manod Mawr (SH 724 446) and is placed in the Region of North Wales (Region A, Sub-Region A3).  The hill is situated with the town of Blaenau Ffestiniog to the west south-west and is positioned above the small mountain lake of Llyn y Drum Boeth which is to its east.

The hill can be accessed via a public footpath from Blaenau Ffestiniog and can be combined with its namesake and also newly crowned Uchaf which is positioned at SH 72020 46289, an alternate and longer ascent can start from above Llan Ffestiniog using a track beside the course of the Afon Teigl.  However, the summit of this hill is not on open access land and it is positioned on the periphery of quarry spoil, therefore permission should be sought to visit, but as the summit is relatively close to a public footpath and with open access land to its north, east and south, common sense should prevail and if wanting to visit the summit there is likely to be no objection to doing so.

The name of the hill is Drum Boeth and its addition to Uchaf status is due to analysis of LIDAR data by Aled Williams.  LIDAR (Light Detection & Ranging) is highly accurate height data that is now freely available for much of England and Wales.

Aled’s analysis of LIDAR data gives the hill the following details:


Drum Boeth

Summit Height:  506.6m

Summit Grid Reference:  SH 71721 46419

Bwlch Height:  490.5m

Bwlch Grid Reference:  SH 71821 46454

Drop:  16.1m


Therefore, the 506.6m LIDAR data produced for the summit position at SH 71721 46419 and the 490.5m LIDAR data produced for the bwlch position at SH 71821 46454 gives this hill 16.1m of drop, which is sufficient for its addition to Uchaf status, with the details from the Trimble GeoXH 6000 survey being 506.8m (converted to OSGM15) summit at SH 71724 46417 and 490.4m (converted to OSGM15) bwlch at SH 71823 46452, giving this hill 16.4m of drop


The full details for the hill are:

Cardinal Hill:  Manod Mawr

Summit Height:  506.8m (converted to OSGM15, Trimble data)

Name:  Drum Boeth

OS 1:50,000 map:  115

Summit Grid Reference:  SH 71721 46419 
  
Drop:  16.4m (converted to OSGM15, Trimble data)


This now brings the overall total for Yr Uchafion / The Welsh 500m P15s to 630 hills with the overall total for the 500m Sub-Uchaf category remaining at 25.

The additions, reclassifications and deletions to Yr Uchafion / The Welsh 500m P15s reported on Mapping Mountains are ills of wales as follows:



UCHAF ADDITIONS






Drum Boeth (LIDAR data and Trimble survey) (SH 71724 46417) added as an Uchaf with 16.4m of drop





500m SUB UCHAF RECLASSIFICATIONS TO UCHAF






UCHAF RECLASSIFICATIONS TO 500m SUB-UCHAF










UCHAF RECLASSIFICATIONS TO 490m SUB-UCHAF






UCHAF DELETIONS





Drum Boeth (SH 717 464) confirmed via LIDAR data and a Trimble survey as an Uchaf

Myrddyn Phillips and Aled Williams (April 2017)



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