Mapping Mountains – Hill Reclassifications – Welsh Highlands – Uchafion Cymru

Bryn Llochesau (SN 824 807) – Welsh Highland Sub deletion 

There has been a deletion 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 for the Welsh Highlands – Uchafion Cymru list authored by Aled Williams and Myrddyn Phillips. 

LIDAR image of Bryn Llochesau (SN 824 807)

The criteria for the list that this deletion applies to are:

Welsh Highlands – Uchafion Cymru – Welsh hills at or above 500m in height with 15m minimum drop, with an accompanying sub list entitled the Welsh Highland Subs, the criteria for which is all Welsh hills at or above 500m in height with 10m or more and below 15m of drop.  This list is authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and the latest update relating to the list published on Mapping Mountains in January 2023.

Welsh Highlands - Uchafion Cymru by Myrddyn Phillips and Aled Williams

The name the hill is listed by is Bryn Llochesau and it is adjoined to the Y Garn group of hills, which are situated in the northern part of South Wales (Region B, Sub-Region B1), and it is positioned with the A44 road to its north, the B4343 road and A4120 road to its west and a minor road to its south, and has the village of Ponterwyd towards the west. 

Extract from the Ordnance Survey 1:50,000 Landranger map

When the initial P10 sub list was completed in June 2020 this hill was listed with an estimated c 10m of drop, based on the 1849ft (563.6m) imperial summit height that appeared on the Ordnance Survey series of Six-Inch maps (rounded up to 564m on the Ordnance Survey 1:50,000 Landranger map) and an estimated c 554m bwlch height based on interpolation of 10m contouring between 550m – 560m. 

Extract from the Ordnance Survey series of Six-Inch maps

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 deletion of this hill from Welsh Highland Sub status is due to LIDAR analysis, resulting in a 563.8m summit height and a 554.1m bwlch height, with these values giving this hill 9.7m of drop, which is insufficient for it to be classified as a Welsh Highland Sub. 

 

The full details for the hill are: 

Group:  Y Garn

Name:  Bryn Llochesau

OS 1:50,000 map:  135, 136

Summit Height:  563.8m (LIDAR)

Summit Grid Reference:  SN 82447 80795 (LIDAR)

Bwlch Height:  554.1m (LIDAR)

Bwlch Grid Reference:  SN 82319 80472 (LIDAR)   

Drop:  9.7m (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 (April 2023)