Rhos Trebared (SN 173 475) – Lesser Dominant deletion
There has been a deletion to the list of the Y Trechol – The Dominant Hills of Wales, with the summit height, bwlch height and their locations, the drop, dominance and status of the hill derived from LIDAR analysis conducted by Myrddyn Phillips.
LIDAR image of Rhos Trebared (SN 173 475) |
The criteria for the list that this deletion
applies to are:
Y Trechol - The Dominant Hills of
Wales - Welsh P30 hills whose prominence
equal or exceed half that of their absolute height. With the
criteria for Lesser Dominant status being those additional Welsh P30 hills whose
prominence is between one third and half that of their absolute height. The list is authored by Myrddyn Phillips with
the Introduction to the start of the Mapping Mountains publication of this list
appearing on the 3rd December 2015, and the list is now available in its entirety on Mapping Mountains in Google Doc format.
Y Trechol - The Dominant Hills of Wales by Myrddyn Phillips |
The name the hill is now listed by is Rhos Trebared
and this was derived from local enquiry, and it is adjoined to the Mynydd Bach group of hills, which are situated in the western part of South
Wales (Region B, Sub-Region B1), and
it is positioned with the coast to its north-west, the B4548 road to its
north-east and a minor road to its south, and has the town of Aberteifi
(Cardigan) towards the south.
When the original 30-99m height band of Welsh P30 hills published on Geoff Crowder’s v-g.me website were standardised and
interpolated heights and drop values also included, this hill was listed with 30m
of drop and 43.48% dominance, based on the 69m summit spot height and the 39m
bwlch spot height that appear on the Ordnance Survey 1:50,000 Landranger and 1:25,000
Explorer map.
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 deletion of this hill from Lesser
Dominant status is due to LIDAR analysis, resulting in a 70.3m summit height
and a 40.3m bwlch height, with these values giving this hill 29.9m of drop, which
is insufficient for this hill to be classified as a Lesser Dominant.
The full details for the hill are:
Group: Mynydd Bach
Name: Rhos Trebared
OS 1:50,000 map: 145
Summit Height: 70.3m
(LIDAR)
Summit Grid Reference:
SN
17391 47521 (LIDAR)
Bwlch Height: 40.3m
(LIDAR)
Bwlch Grid Reference:
SN 17728 47659 (LIDAR)
Drop: 29.9m (LIDAR)
Dominance: drop insufficient
for qualification
Myrddyn Phillips (February 2023)
No comments:
Post a Comment